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Lin Y, Wang H, Xu J, Huang Y, Gong W, Wang Q, Huang Z, Xie S, Lin J. High spatio-temporal resolution measurement of A 1 R and A 2A R interactions combined with Iem-spFRET and E-FRET methods. JOURNAL OF BIOPHOTONICS 2021; 14:e202100172. [PMID: 34328277 DOI: 10.1002/jbio.202100172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/17/2021] [Accepted: 07/27/2021] [Indexed: 06/13/2023]
Abstract
A1 R-A2A R heterodimers regulate striatal glutamatergic neurotransmission. However, few researches about kinetics have been reported. Here, we combined Iem-spFRET and E-FRET to investigate the kinetics of A1 R and A2A R interaction. Iem-spFRET obtains the energy transfer efficiency of the whole cell. E-FRET gets energy transfer efficiency with high spatial resolution, whereas, it was prone to biases because background was easily selected due to manual operation. To study the interaction with high spatio-temporal resolution, Iem-spFRET was used to correct the deviation of E-FRET. In this paper, A1 R and A2A R interaction was monitored, and the changes of FRET efficiency of the whole or/and partial cell membrane were described. The results showed that activation of A1 R or A2A R leads to rapid aggregation, inhibition of A1 R or A2A R leads to slow segregation, and the interaction is reversible. These results demonstrated that combination of Iem-spFRET and E-FRET could measure A1 R and A2A R interaction with high spatio-temporal resolution.
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Affiliation(s)
- Yating Lin
- MOE Key Laboratory of OptoElectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian, China
| | - Haoyu Wang
- MOE Key Laboratory of OptoElectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian, China
| | - Jianshu Xu
- MOE Key Laboratory of OptoElectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian, China
| | - Yiming Huang
- MOE Key Laboratory of OptoElectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian, China
| | - Wei Gong
- MOE Key Laboratory of OptoElectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian, China
| | - Qiwen Wang
- MOE Key Laboratory of OptoElectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian, China
| | - Zufang Huang
- MOE Key Laboratory of OptoElectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian, China
| | - Shusen Xie
- MOE Key Laboratory of OptoElectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian, China
| | - Juqiang Lin
- MOE Key Laboratory of OptoElectronic Science and Technology for Medicine and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, Fujian, China
- School of Opto-electronic and Communication Engineering, Xiamen University of Technology, Xiamen, Fujian, China
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Fujimoto T, Parmryd I. Interleaflet Coupling, Pinning, and Leaflet Asymmetry-Major Players in Plasma Membrane Nanodomain Formation. Front Cell Dev Biol 2017; 4:155. [PMID: 28119914 PMCID: PMC5222840 DOI: 10.3389/fcell.2016.00155] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 12/27/2016] [Indexed: 01/26/2023] Open
Abstract
The plasma membrane has a highly asymmetric distribution of lipids and contains dynamic nanodomains many of which are liquid entities surrounded by a second, slightly different, liquid environment. Contributing to the dynamics is a continuous repartitioning of components between the two types of liquids and transient links between lipids and proteins, both to extracellular matrix and cytoplasmic components, that temporarily pin membrane constituents. This make plasma membrane nanodomains exceptionally challenging to study and much of what is known about membrane domains has been deduced from studies on model membranes at equilibrium. However, living cells are by definition not at equilibrium and lipids are distributed asymmetrically with inositol phospholipids, phosphatidylethanolamines and phosphatidylserines confined mostly to the inner leaflet and glyco- and sphingolipids to the outer leaflet. Moreover, each phospholipid group encompasses a wealth of species with different acyl chain combinations whose lateral distribution is heterogeneous. It is becoming increasingly clear that asymmetry and pinning play important roles in plasma membrane nanodomain formation and coupling between the two lipid monolayers. How asymmetry, pinning, and interdigitation contribute to the plasma membrane organization is only beginning to be unraveled and here we discuss their roles and interdependence.
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Affiliation(s)
- Toyoshi Fujimoto
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine Nagoya, Japan
| | - Ingela Parmryd
- Science for Life Laboratory, Medical Cell Biology, Uppsala University Uppsala, Sweden
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3
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Abstract
The Fluid-Mosaic Membrane Model of cell membrane structure was based on thermodynamic principals and the available data on component lateral mobility within the membrane plane [Singer SJ, Nicolson GL. The Fluid Mosaic Model of the structure of cell membranes. Science 1972; 175: 720-731]. After more than forty years the model remains relevant for describing the basic nano-scale structures of a variety of biological membranes. More recent information, however, has shown the importance of specialized membrane domains, such as lipid rafts and protein complexes, in describing the macrostructure and dynamics of biological membranes. In addition, membrane-associated cytoskeletal structures and extracellular matrix also play roles in limiting the mobility and range of motion of membrane components and add new layers of complexity and hierarchy to the original model. An updated Fluid-Mosaic Membrane Model is described, where more emphasis has been placed on the mosaic nature of cellular membranes where protein and lipid components are more crowded and limited in their movements in the membrane plane by lipid-lipid, protein-protein and lipid-protein interactions as well as cell-matrix, cell-cell and cytoskeletal interactions. These interactions are important in restraining membrane components and maintaining the unique mosaic organization of cell membranes into functional, dynamic domains.
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Affiliation(s)
- Garth L Nicolson
- The Institute for Molecular Medicine, Department of Molecular Pathology, Huntington Beach, CA, USA
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4
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Induction of non-lamellar lipid phases by antimicrobial peptides: a potential link to mode of action. Chem Phys Lipids 2010; 163:82-93. [PMID: 19799887 DOI: 10.1016/j.chemphyslip.2009.09.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 09/04/2009] [Accepted: 09/23/2009] [Indexed: 12/24/2022]
Abstract
Antimicrobial peptides are naturally produced by numerous organisms including insects, plants and mammals. Their non-specific mode of action is thought to involve the transient perturbation of bacterial membranes but the molecular mechanism underlying the rearrangement of the lipid molecules to explain the formation of pores and micelles is still poorly understood. Biological membranes mostly adopt planar lipid bilayers; however, antimicrobial peptides have been shown to induce non-lamellar lipid phases which may be intimately linked to their proposed mechanisms of action. This paper reviews antimicrobial peptides that alter lipid phase behavior in three ways: peptides that induce positive membrane curvature, peptides that induce negative membrane curvature and peptides that induce cubic lipid phases. Such structures can coexist with the bilayer structure, thus giving rise to lipid polymorphism induced upon addition of antimicrobial peptides. The discussion addresses the implications of induced lipid phases for the mode of action of various antimicrobial peptides.
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5
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Transmembrane cholesterol migration in planar lipid membranes measured with Vibrio cholerae cytolysin as molecular tool. Biochimie 2009; 91:620-3. [DOI: 10.1016/j.biochi.2009.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Accepted: 03/12/2009] [Indexed: 01/12/2023]
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6
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Kurilenko AV, Zakhartsev MV, Chelomin VP. In vitro effect of copper ions on transbilayer distribution of aminophospholipids in synaptosomal membrane of walleye pollock (Theragra chalcogramma). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2002; 58:131-136. [PMID: 12007869 DOI: 10.1016/s0166-445x(01)00224-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Effect of copper ions on lipid matrix organization of synaptosomal membrane of the marine fish Theragra chalcogramma was investigated. It was demonstrated that interaction of copper ions with these membrane stimulated the process of lipid peroxidation and caused changes in the transbilayer distribution of aminophospholipids. Accessibility of phosphatidylethanolamine was increased more than twice, and of phosphatidylserine more than ten times, that can be explained by changes in asymmetrical structure of lipid matrix of synaptosomal membrane. We suggested, that the main mechanism of copper-stimulated damage in transbilayer organization of the membrane is oxidation of membrane protein sulfhydryl groups.
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Affiliation(s)
- A V Kurilenko
- Pacific Oceanological Institute, Russian Academy of Sciences, Vladivostok 690041, Russia
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7
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Müller P, Schiller S, Wieprecht T, Dathe M, Herrmann A. Continuous measurement of rapid transbilayer movement of a pyrene-labeled phospholipid analogue. Chem Phys Lipids 2000; 106:89-99. [PMID: 10878238 DOI: 10.1016/s0009-3084(00)00134-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The excimer forming capacity of the fluorescent moiety pyrene is employed to measure continuously the transbilayer (re)distribution of a pyrene-labeled phosphatidylcholine analogue (pyPC) in liposomal membranes. pyPC with a lauroyl residue (sn-1 position) and a short (butyroyl) fatty acid chain (sn-2 position) bearing the pyrene moiety incorporates rapidly into the outer leaflet of liposomes. The fluorescence intensities of excimers (I(E)) and of monomers (I(M)) of pyPC depend on the concentration of the analogue in a membrane leaflet. Therefore, the redistribution of pyPC from the outer to the inner leaflet can be followed by changes of the ratio I(E)/I(M). The transbilayer movement of pyPC in pure phospholipid vesicles is very slow indicated by a constant I(E)/I(M). However, addition of membrane active peptides (melittin, magainin 2 amide or a mutant of magainin 2 amide) induced a rapid translocation of pyPC from the outer to the inner leaflet. An approach is presented which allows estimating the transbilayer distribution of pyPC from the measured ratio I(E)/I(M).
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Affiliation(s)
- P Müller
- Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, Institut für Biologie/Biophysik, Invalidenstrasse 43, D-10115, Berlin, Germany. peter=
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8
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Umeda M, Emoto K. Membrane phospholipid dynamics during cytokinesis: regulation of actin filament assembly by redistribution of membrane surface phospholipid. Chem Phys Lipids 1999; 101:81-91. [PMID: 10810927 DOI: 10.1016/s0009-3084(99)00057-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To study molecular motion and function of membrane phospholipids, we have developed various probes which bind specifically to certain phospholipids. Using a novel peptide probe, RoO9-0198, which binds specifically to phosphatidylethanolamine (PE) in biological membranes, we have analyzed the cell surface movement of PE in dividing CHO cells. We found that PE was exposed on the cell surface specifically at the cleavage furrow during the late telophase of cytokinesis. PE was exposed on the cell surface only during the late telophase and no alteration in the distribution of the plasma membranebound peptide was observed during the cytokinesis, suggesting that the surface exposure of PE reflects the enhanced transbilayer movement of PE at the cleavage furrow. Furthermore, cell surface immobilization of PE induced by adding of the cyclic peptide coupled with streptavidin to prometaphase cells effectively blocked the cytokinesis at late telophase. The peptide-streptavidin complex bound specifically to cleavage furrow and inhibited both actin filament disassembly at cleavage furrow and subsequent plasma membrane fusion. Binding of the peptide complex to interphase cells also induced immediate disassembly of stress fibers followed by assembly of cortical actin filaments to the local area of plasma membrane where the peptide complex bound. The cytoskeletal reorganizations caused by the peptide complex were fully reversible; removal of the surface-bound peptide complex by incubating with PE-containing liposome caused gradual disassembly of the cortical actin filaments and subsequent formation of stress fibers. These observations suggest that the redistribution of plasma membrane phospholipids act as a regulator of actin cytoskeleton organization and may play a crucial role in mediating a coordinate movement between plasma membrane and actin cytoskeleton to achieve successful cell division.
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Affiliation(s)
- M Umeda
- Department of Molecular Biodynamics, The Tokyo Metropolitan Institute of Medical Science (RINSHOKEN), Japan.
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9
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Tocanne JF, Cézanne L, Lopez A, Piknova B, Schram V, Tournier JF, Welby M. Lipid domains and lipid/protein interactions in biological membranes. Chem Phys Lipids 1994; 73:139-58. [PMID: 8001179 DOI: 10.1016/0009-3084(94)90179-1] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In the fluid mosaic model of membranes, lipids are organized in the form of a bilayer supporting peripheral and integral proteins. This model considers the lipid bilayer as a two-dimensional fluid in which lipids and proteins are free to diffuse. As a direct consequence, both types of molecules would be expected to be randomly distributed within the membrane. In fact, evidences are accumulating to indicate the occurrence of both a transverse and lateral regionalization of membranes which can be described in terms of micro- and macrodomains, including the two leaflets of the lipid bilayer. The nature of the interactions responsible for the formation of domains, the way they develop and the time- and space-scale over which they exist represent today as many challenging problems in membranology. In this report, we will first consider some of the basic observations which point to the role of proteins in the transverse and lateral regionalization of membranes. Then, we will discuss some of the possible mechanisms which, in particular in terms of lipid/protein interactions, can explain lateral heterogenities in membranes and which have the merit of providing a thermodynamic support to the existence of lipid domains in membranes.
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Affiliation(s)
- J F Tocanne
- Laboratoire de Pharmacologie et Toxicologie Fondamentales du CNRS, Dpt III, Toulouse, France
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Tocanne JF, Dupou-Cézanne L, Lopez A. Lateral diffusion of lipids in model and natural membranes. Prog Lipid Res 1994; 33:203-37. [PMID: 8022844 DOI: 10.1016/0163-7827(94)90027-2] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- J F Tocanne
- CNRS, Département III: Glycoconjugués et Biomembranes, Toulouse, France
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11
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Protein-Mediated Phospholipid Movement in Red Blood Cells. CURRENT TOPICS IN MEMBRANES 1994. [DOI: 10.1016/s0070-2161(08)60976-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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12
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Zachowski A. Phospholipids in animal eukaryotic membranes: transverse asymmetry and movement. Biochem J 1993; 294 ( Pt 1):1-14. [PMID: 8363559 PMCID: PMC1134557 DOI: 10.1042/bj2940001] [Citation(s) in RCA: 636] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- A Zachowski
- Institut de Biologie Physico-Chimique, Paris, France
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13
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Supernovich C, Crain R, Rosenberg P. Phosphatidylcholine asymmetry in electroplax from the electric eel: use of a phosphatidylcholine exchange protein. J Neurochem 1991; 57:575-84. [PMID: 2072103 DOI: 10.1111/j.1471-4159.1991.tb03788.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Phosphatidylcholine asymmetry in the inner and outer leaflets of the plasma membrane bilayer of the innervated and noninnervated surfaces of the electroplax cell was determined, using a phosphatidylcholine exchange protein. The exchange protein from bovine liver catalyzed the exchange of phosphatidylcholine from small unilamellar vesicles to the outer monolayer of the plasma membrane bilayer. The exchange protein did not penetrate to the inner monolayer of the plasma membrane, did not modify the permeability of the electroplax, and did not alter the phospholipid or cholesterol content of the electroplax. In the innervated plasma membrane, 42% of the phosphatidylcholine is in the outer leaflet, 33% is in the inner leaflet, and 25% is inaccessible to the exchange protein. Corresponding values for the noninnervated plasma membrane are 56, 26, and 18%, respectively. These results are similar to phosphatidylcholine asymmetry in other biological membranes. This unique cell can be used as a model to test the effects on phospholipid asymmetry of compounds that act on the membrane.
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Affiliation(s)
- C Supernovich
- Section of Pharmacology and Toxicology, School of Pharmacy, University of Connecticut, Storrs 06269
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14
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Koval M, Pagano RE. Intracellular transport and metabolism of sphingomyelin. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1082:113-25. [PMID: 2007175 DOI: 10.1016/0005-2760(91)90184-j] [Citation(s) in RCA: 177] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
SM is unique among the phospholipids because it is restricted to the lumenal aspect of organelles involved in the secretory and endocytic pathways. Given the intracellular sites of SM biosynthesis and hydrolysis, and the interconnections between these sites by vesicle-mediated transport pathways, the basic mechanism for maintaining the intracellular distribution of SM seems clear. It remains to be determined how SM metabolism and transport are coordinated to maintain the SM content of each organelle. For example, the size of the SM pool at the cell surface is maintained by regulation of at least five processes: transport of newly synthesized SM from the Golgi apparatus, plasma membrane lipid recycling, local SM synthesis, local SM hydrolysis, and SM transport from the cell surface to lysosomes. Although SM cannot undergo spontaneous transbilayer movement, SM metabolism generates both DAG, Cer and (indirectly) SPhB which can rapidly 'flip-flop', and thus gain access to the cytoplasmic leaflet of a membrane. It is of particular interest that these lipid species may be involved in the regulation of PK-C, suggesting that SM metabolism could play a role in signal transduction. However, physiological effects of endogenous Cer and SPhB remain elusive, even though the pharmacological effect of SPhB on PK-C is well established. Aside from the direct generation of second messengers, stimulation of SM hydrolysis has also been shown to induce cholesterol movement from the cell surface to intracellular membranes. It is not known whether this reflects the possibility that cholesterol may act as a second messenger. Alternatively, this phenomenon suggests that SM metabolism may cause rapid changes in the physical properties of the cell surface. For example, erythrocytes extensively treated with exogenously-added SMase will undergo endovesiculation It is tempting to speculate that any involvement of SM in the regulation of intracellular processes requires a combination of both the generation of biochemical second messengers and the alteration of membrane biophysical properties that can result from SM metabolism.
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Affiliation(s)
- M Koval
- Carnegie Institution of Washington, Department of Embryology, Baltimore, MD 21210-3301
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15
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Beck A, Heissler D, Duportail G. 1-Palmitoyl-2-[3-(diphenylhexatrienyl) propanoyl]-sn-glycero-3-phosphoethanolamine as a fluorescent membrane probe. Synthesis and partitioning properties. Chem Phys Lipids 1990. [DOI: 10.1016/0009-3084(90)90144-g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Abstract
Membranes allow the rapid passage of unchanged lipids. Phospholipids on the other hand diffuse very slowly from one monolayer to another with a half-time of several hours. This slow spontaneous movement in a pure lipid bilayer can be selectively modulated in biological membranes by intrinsic proteins. In microsomes, and probably in bacterial membranes, non-specific phospholipid flippases allow the rapid redistribution of newly synthesized phospholipids. In eukaryotic plasma membranes, aminophospholipid translocase selectively pumps phosphatidylserine (PS) and phosphatidylethanolamine (PE) from the outer to the inner leaflet and establishes a permanent lipid asymmetry. The discovery of an aminophospholipid translocase in chromaffin granules proves that eukaryotic organelles may also contain lipid translocators.
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Affiliation(s)
- A Zachowski
- Institut de Biologie Physico-Chimique, Paris, France
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17
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Translocation and distribution of phospholipids across eukaryotic plasma membranes. SPRINGER SERIES IN BIOPHYSICS 1990. [DOI: 10.1007/978-3-642-74471-6_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Bonini de Romanelli IC, Aveldaño MI, Barrantes FJ. Asymmetric distribution of phospholipids in acetylcholine receptor-rich membranes from T. marmorata electric organ. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1990; 22:785-9. [PMID: 2401378 DOI: 10.1016/0020-711x(90)90016-v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
1. The distribution of phospholipids between the two leaflets of the lipid bilayer in acetylcholine receptor (AChR)-rich membranes from T. marmorata has been examined with two complementary techniques: chemical derivatization with the membrane-impermeable reagent trinitrobenzenesulphonate (TNBS) and B.cereus phospholipase C hydrolysis. 2. AChR-membranes were reacted with TNBS at 0-4 and 37 degrees C and the accessibility of their aminophospholipids was compared to that of rod outer segment and erythrocyte membranes. The results indicate that more of the total ethanolamine glycerophospholipid (EGP) than of the total phosphatidylserine (PS) is located in the outer monolayer. 3. Nearly half the phospholipid content of AChR membranes is hydrolyzed by phospholipase C with a half-time of ca. 1.6 min at 25 degrees C. Consistent with the TNBS results, more of the total EGP than of the total PS is degraded. Beyond 3 min the reaction slows down, relatively smaller additional amounts of lipids are hydrolyzed, and all phospholipid classes are attacked to a similar extent, indicating that after half the lipid is removed all phospholipids become accessible to the enzyme. 4. The results indicate that the outer leaflet of the bilayer is richer in ethanolamine and choline glycerophospholipids, whereas phosphatidylinositol, most of the sphingomyelin, and ca 65% of the PS are located on the inner leaflet.
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Affiliation(s)
- I C Bonini de Romanelli
- Instituto de Investigaciones Bioquimicas, Universidad Nacional del Sur, Bahia Blanca, Argentina
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19
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Crowell KM, Lutz F. Pseudomonas aeruginosa cytotoxin: the influence of sphingomyelin on binding and cation permeability increase in mammalian erythrocytes. Toxicon 1989; 27:531-40. [PMID: 2501911 DOI: 10.1016/0041-0101(89)90114-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A cytotoxic protein isolated from Pseudomonas aeruginosa damages the plasma membranes of many mammalian cells by forming pores. We studied binding of the 125I-cytotoxin and the resulting increase of cation permeability in erythrocytes of various mammalian species. The sensitivity of red blood cells was inversely related to the relative sphingomyelin content in their external surface. Thus, erythrocytes with a sphingomyelin to phosphatidylcholine ratio below 1 (dog, rat, rabbit and man) were sensitive, whereas red blood cells with a ratio above 1 (pig, cattle and sheep) were not attacked even with 100-fold higher cytotoxin concentrations. At 37 degrees C 6.8 +/- 1.2 x 10(3) molecules of 125I-cytotoxin were bound per rabbit erythrocyte (KD = 59 nM), whereas no binding occurred to cattle cells. Cleavage of sphingomyelin by sphingomyelinase C from Bacillus cereus (EC 3.1.4.12) triggered a dose-dependent enhancement in binding and permeability increase, particularly in red blood cells with a high proportion of sphingomyelin. The KDs for all animal species investigated were 53-60 nM. Pretreatment with mainly phosphatidylcholine-hydrolyzing phospholipases D from Streptomyces chromofuscus and cabbage (EC 3.1.4.4) or phospholipase C from Bacillus cereus (EC 3.1.4.3) did not influence the cytotoxin effect. The negative correlation between susceptibility and the proportion of sphingomyelin in plasma membranes suggests a binding site close to sphingomyelin.
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Affiliation(s)
- K M Crowell
- Institut für Pharmakologie und Toxikologie, Justus-Liebig-Universität Giessen, F.R.G
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20
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Rosenberg P, Ghassemi A, Condrea E, Dhillon D, Yang CC. Do chemical modifications dissociate between the enzymatic and pharmacological activities of beta bungarotoxin and notexin? Toxicon 1989; 27:137-59. [PMID: 2718187 DOI: 10.1016/0041-0101(89)90128-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have measured enzymatic, hemolytic and anticoagulant activities, lethal potencies and effects on contractions of the phrenic nerve-diaphragm preparation, by chemically modified derivatives of beta bungarotoxin (beta BuTX) and notexin, two presynaptically acting toxins which have PLA2 activity. The following chemical modifications of beta BuTX were tested: alkylation and methylation of histidine 48, alkylation of tryptophan 19, sulfonylation of tyrosine 68, oxidation of methionines 6 and 8, semicarbazide addition under varied conditions to carboxyl groups, varied extents of carbamylation or trinitrophenylation of lysines and guanidination of all lysines with or without trinitrophenylation of the N-terminal asparagine. Only the histidine, tryptophan and tyrosine residues were modified in notexin. The results obtained were compared with those previously obtained using chemically modified derivatives of Naja nigricollis and Naja naja atra PLA2 enzymes which do not have a specific presynaptic site of action. The results with oxidized methionine and lysine-modified derivatives of beta BuTX are supportive of the suggestions of others that the N-terminal region and basic residues away from the enzymatic active region contribute towards the beta type presynaptic neurotoxicity of the PLA2 toxins. Using modified derivatives of beta BuTX and notexin, the dissociations between enzymatic activities and pharmacological properties were not as marked as previously observed with N. nigricollis and N. n. atra PLA2; nevertheless, several dissociations were noted. We conclude that, just as with non-presynaptically acting PLA2 enzymes, some pharmacological actions of presynaptically acting PLA2 toxins may occur independently of phospholipid hydrolysis.
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Affiliation(s)
- P Rosenberg
- Section of Pharmacology and Toxicology, University of Connecticut, School of Pharmacy, Storrs 06268
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21
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Sune A, Vidal M, Morin P, Sainte-Marie J, Bienvenue A. Evidence for bidirectional transverse diffusion of spin-labeled phospholipids in the plasma membrane of guinea pig blood cells. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 946:315-27. [PMID: 2850004 DOI: 10.1016/0005-2736(88)90407-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The distribution and transverse diffusion kinetics of four spin-labeled phospholipid analogues (two with choline heads: phosphatidylcholine (PC) and sphingomyelin (SM); two with amino heads: phosphatidylserine (PS) and phosphatidylethanolamine (PE) were studied in the plasma membrane of guinea pig blood cells: erythrocytes, reticulocytes, and leukemic lymphocytes. Nitroxide reduction by the internal content of the cells was used as an indicator to determine the phospholipids that penetrated the cells. The reduction rates were in the order, PS greater than PE greater than PC greater than SM in all cells. Reoxidation of phospholipids extracted by serum albumin revealed the distribution of the phospholipids at a given time. In all cells, the distribution equilibrium was reached in less than 2 h and the amounts left in the external leaflet were in the following proportional order: PS less than PE less than PC less than SM. In the erythrocytes and especially in the reticulocytes, the shape change induced by adding phospholipids relaxed partially or completely at a lower speed but kept the same proportional order as at equilibrium. All the results were analyzed quantitatively with a simple kinetic model including the rates of transverse diffusion (flip and flop), the exchange between plasma membrane and internal membranes, and the reduction rate of free radicals (determined in either the internal or external membrane leaflet). The calculated rate constants of transverse diffusion varied from 2 x 10(-3) to 1.2 x 10(-1) min-1 for the flip and from 4 x 10(-3) to 1.2 x 10(-1) for the flop, depending on the polar head and the cell type. Possible interpretations of the external phospholipid reduction mechanism and cell deformation are discussed.
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Affiliation(s)
- A Sune
- Laboratoire de Biologie Physico-chimique, UA 530 CNRS, USTL, Montpellier, France
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Affiliation(s)
- K J Kako
- Department of Physiology, School of Medicine, University of Ottawa, Ontario, Canada
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McLaughlin J. Trypanosoma rhodesiense: antigenicity and immunogenicity of flagellar pocket membrane components. Exp Parasitol 1987; 64:1-11. [PMID: 3609224 DOI: 10.1016/0014-4894(87)90002-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A low density membrane fraction, isolated from the bloodstream stage of Trypanosoma rhodesiense and enriched in flagellar pocket membrane, was characterized with regard to antigenicity using antibodies raised against purified flagellar pocket membrane. Mild trypsinolysis of flagellar pocket membrane released two small peptides (Mr = 13-16 X 10(3)) separated by chromatofocusing (pI = 6.8 and 5.8) that were antigenic as monitored by fused rocket immunoelectrophoresis. Both of these antigenic peptides were enriched in relative fluorescence when flagellar pocket membrane was prepared from surface labeled (fluorescamine-beta-cyclodextrin) trypanosomes, indicating that cleaved peptides were on the external (luminal) side of the flagellar pocket membrane. More extensive release of fluorescamine labeled flagellar pocket membrane components was affected using mild detergent treatment (0.15% Zwittergent 3-12/0.4% Triton X-100), crossed immunoelectrophoresis separating two prominent antigens was more pronounced after incubation of flagellar pocket membrane with either porcine pancreas phospholipase A2 or umbilical cord sphingomyelinase. The use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and subsequent electroblotting to nitrocellulose also revealed two principal flagellar pocket membrane antigens (Mr approximately 60 and 66 X 10(3)), the latter showing greater release after exposure to sphingomyelinase or phospholipase, compared to mild detergent or 50 mM acetate, pH 5.0. Both antigens were glycoprotein as judged by electroblotting and the use of concanavalin A conjugated horseradish peroxidase as probe. Neither flagellar pocket membrane antigen was found to react with monoclonal antibodies prepared against T. rhodesiense variable surface antigen. The use of flagellar pocket membrane in the presence of Freund's complete adjuvant was found to protect mice against challenge infections with either the CP344 clone or uncloned CT Well-come isolate of T. rhodesiense.
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Pasquale L, Winiski A, Oliva C, Vaio G, McLaughlin S. An experimental test of new theoretical models for the electrokinetic properties of biological membranes. The effect of UO2++ and tetracaine on the electrophoretic mobility of bilayer membranes and human erythrocytes. J Gen Physiol 1986; 88:697-718. [PMID: 3794637 PMCID: PMC2228859 DOI: 10.1085/jgp.88.6.697] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
For a large smooth particle with charges at the surface, the electrophoretic mobility is proportional to the zeta potential, which is related to the charge density by the Gouy-Chapman theory of the diffuse double layer. This classical model adequately describes the dependence of the electrophoretic mobility of phospholipid vesicles on charge density and salt concentration, but it is not applicable to most biological cells, for which new theoretical models have been developed. We tested these new models experimentally by measuring the effect of UO2++ on the electrophoretic mobility of model membranes and human erythrocytes in 0.15 M NaCl at pH 5. We used UO2++ for these studies because it should adsorb specifically to the bilayer surface of the erythrocyte and should not change the density of fixed charges in the glycocalyx. Our experiments demonstrate that it forms high-affinity complexes with the phosphate groups of several phospholipids in a bilayer but does not bind significantly to sialic acid residues. As observed previously, UO2++ adsorbs strongly to egg phosphatidylcholine (PC) vesicles: 0.1 mM UO2++ changes the zeta potential of PC vesicles from 0 to +40 mV. It also has a large effect on the electrophoretic mobility of vesicles formed from mixtures of PC and the negative phospholipid phosphatidylserine (PS): 0.1 mM UO2++ changes the zeta potential of PC/PS vesicles (10 mol % PS) from -13 to +37 mV. In contrast, UO2++ has only a small effect on the electrophoretic mobility of either vesicles formed from mixtures of PC and the negative ganglioside GM1 or erythrocytes: 0.1 mM UO2++ changes the apparent zeta potential of PC/GM1 vesicles (17 mol % GM1) from -11 to +5 mV and the apparent zeta potential of erythrocytes from -12 to -4 mV. The new theoretical models suggest why UO2++ has a small effect on PC/GM1 vesicles and erythrocytes. First, large groups (e.g., sugar moieties) protruding from the surface of the PC/GM1 vesicles and erythrocytes exert hydrodynamic drag. Second, charges at the surface of a particle (e.g., adsorbed UO2++) exert a smaller effect on the mobility than charges located some distance from the surface (e.g., sialic acid residues).
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Pulido JA, del Hoyo N, Pérez-Albarsanz MA. Composition and fatty acid content of rat ventral prostate phospholipids. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 879:51-5. [PMID: 3768387 DOI: 10.1016/0005-2760(86)90265-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The major phospholipids of rat ventral prostate have been separated and examined using thin-layer chromatography, gas chromatography and mass spectrometry. The main phospholipid classes were choline and ethanolamine glycerophospholipids, accounting for 77.9% of total lipid phosphorus. The prostate also contained small amounts of serine glycerophospholipids and sphingomyelin. The relative proportions of fatty acids in the different phospholipid classes were also determined. Arachidonic acid in prostatic phospholipids is contributed primarily by ethanolamine glycerophospholipids. This fraction contained 65-69 mol% plasmalogens, whereas choline and serine glycerophospholipid fractions contained less than 5 mol% plasmalogens. Ethanolamine, choline and serine plasmalogens contained mainly vinyl ethers of palmitic and stearic aldehydes. Ethanolamine plasmalogens also contained the vinyl ether of oleic aldehyde.
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Devaux PF, Seigneuret M. Specificity of lipid-protein interactions as determined by spectroscopic techniques. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 822:63-125. [PMID: 2988624 DOI: 10.1016/0304-4157(85)90004-8] [Citation(s) in RCA: 201] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Dorne AJ, Joyard J, Block MA, Douce R. Localization of phosphatidylcholine in outer envelope membrane of spinach chloroplasts. J Cell Biol 1985; 100:1690-7. [PMID: 3988805 PMCID: PMC2113847 DOI: 10.1083/jcb.100.5.1690] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have examined the effects of phospholipase C from Bacillus cereus on the extent of phospholipid hydrolysis in envelope membrane vesicles and in intact chloroplasts. When isolated envelope vesicles were incubated in presence of phospholipase C, phosphatidylcholine and phosphatidylglycerol, but not phosphatidylinositol, were totally converted into diacylglycerol if they were available to the enzyme (i.e., when the vesicles were sonicated in presence of phospholipase C). These experiments demonstrate that phospholipase C can be used to probe the availability of phosphatidylcholine and phosphatidylglycerol in the cytosolic leaflet of the outer envelope membrane from spinach chloroplasts. When isolated, purified, intact chloroplasts were incubated with low amounts of phospholipase C (0.3 U/mg chlorophyll) under very mild conditions (12 degrees C for 1 min), greater than 80% of phosphatidylcholine molecules and almost none of phosphatidylglycerol molecules were hydrolyzed. Since we have also demonstrated, by using several different methods (phase-contrast and electron microscopy, immunochemical and electrophoretic analyses) that isolated spinach chloroplasts, and especially their outer envelope membrane, remained intact after mild treatment with phospholipase C, we can conclude that there is a marked asymmetric distribution of phospholipids across the outer envelope membrane of spinach chloroplasts. Phosphatidylcholine, the major polar lipid of the outer envelope membrane, is almost entirely accessible from the cytosolic side of the membrane and therefore is probably localized in the outer leaflet of the outer envelope bilayer. On the contrary, phosphatidylglycerol, the major polar lipid in the inner envelope membrane and the thylakoids, is probably not accessible to phospholipase C from the cytosol and therefore is probably localized mostly in the inner leaflet of the outer envelope membrane and in the other chloroplast membranes.
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Abstract
Recent advances in our understanding of the asymmetric distribution of lipids across nervous system membranes coupled with the application of biophysical techniques to examine transbilayer structure and function have led to the formulation of a new hypothesis. The author hopes that the insights presented herein will stimulate investigation into this developing new field. The theory provides an approach to correlation the accumulation of nervous tissue membrane peroxidative and cross-linking damage, the loss of transbilayer lipid asymmetry, and loss of transbilayer neuroendocrine, transport, secretory and immunoregulatory functions. Central to this scheme is the role of membrane lipid asymmetry in regulation to and/or coupling of transbilayer functions.
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Stubbs CD, Smith AD. The modification of mammalian membrane polyunsaturated fatty acid composition in relation to membrane fluidity and function. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 779:89-137. [PMID: 6229284 DOI: 10.1016/0304-4157(84)90005-4] [Citation(s) in RCA: 1223] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Barrington PL, Condrea E, Soons KR, Yang CC, Rosenberg P. Effect of carboxylate group modification on enzymatic and cardiotoxic properties of snake venom phospholipases A2. Toxicon 1984; 22:743-58. [PMID: 6523504 DOI: 10.1016/0041-0101(84)90157-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
By treating Naja nigricollis and Naja naja atra phospholipase A2 with carbodiimide and semicarbazide, we obtained derivatives having varied numbers of modified carboxylate groups. When tested on artificial and natural substrates, derivatives of both enzymes with a modified carboxylate group at the active site (Asp-49) retained little enzymatic activity (1/41 to 10%). However, the derivatives of N. nigricollis also lost most of their lethal potency (5% of native), while those of N. n. atra retained considerable lethality (29%). Carboxyl modification with protection of Asp-49 in N. n. atra enzyme resulted in a derivative with lethal potency equal to or greater than the native enzyme and enzymatic activity which was low on all substrates (12-17% of native). Similar protection of Asp-49 at the active site in N. nigricollis enzyme produced a derivative with decreased enzymatic activity on artificial substrate (22% of native) and decreased lethality (17-33% of native), but with full enzymatic activity on natural substrates. When tested on electrical and mechanical properties of the isolated perfused heart and the isolated ventricle muscle wall, the derivatives of both enzymes retained considerably more of the cardiotoxic activity than would have been expected based on their residual enzymatic activity. The one exception occurred with the least modified N. nigricollis derivative which had an unaltered Asp-49, this enzyme retained both cardiotoxic activity and full enzymatic activity on natural substrates. The extent of phospholipid hydrolysis following treatment was measured in the isolated heart preparation and in hearts removed from mice following i.v. injection of the phospholipases. Very low levels of phospholipid hydrolysis were observed and no correlation could be made between the extent of hydrolysis and the pharmacological potencies of these enzymes. Modification of the enzymatic active site, whether of Asp-49 in this study of His-48 in prior studies, leads to a large decrease in both enzymatic activity and lethal potency. Asp and Glu residues outside of the enzymatic site contribute significantly to the lethal potency of the N. nigricollis enzyme and to the enzymatic activity of the N. n. atra enzyme. Based on these and previous data we conclude that changes in isoelectric points are not responsible for altered lethal potencies following chemical modification and that some pharmacological effects of snake venom phospholipases A2 are due to a non-enzymatic action, suggesting two distinct but perhaps overlapping active sites.
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Delclos KB, Yeh E, Blumberg PM. Specific labeling of mouse brain membrane phospholipids with [20-3H]phorbol 12-p-azidobenzoate 13-benzoate, a photolabile phorbol ester. Proc Natl Acad Sci U S A 1983; 80:3054-8. [PMID: 6304691 PMCID: PMC393972 DOI: 10.1073/pnas.80.10.3054] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
As part of our effort to characterize receptors for the phorbol ester tumor promoters, a phorbol ester photoaffinity probe, [20-3H]phorbol 12-p-azidobenzoate 13-benzoate (PaBzBz), was synthesized. In the dark, PaBzBz bound reversibly to brain particulate fractions with a dissociation constant (Kd) of 0.81 +/- 0.09 x 10(-9) M. Specific binding of PaBzBz, at a concentration equal to its Kd, represented 85% of the total bound. At saturation, 24 +/- 5 pmol of PaBzBz were bound per mg of brain protein, a level similar to that observed with [20-3H]phorbol 12,13-dibutyrate. Under the conditions used (concentrations greater than the Kd for PaBzBz), irradiation caused 45% of the PaBzBz binding to become irreversible. Most of the binding (approximately equal to 60%), including most of the specific irreversible binding, was to phospholipid rather than to protein. Based on susceptibility to enzymatic digestion and on chromatographic mobility, the specifically labeled phospholipids were identified as phosphatidylserine, phosphatidylethanolamine, and phosphatidylethanolamine plasmalogen. Although the PaBzBz specifically labeled lipid, labeling was blocked by pretreatment of membranes at 100 degrees C for 5 min or by papain digestion. Therefore, it seems likely that the identified lipids are specifically associated with a protein receptor and are preferentially labeled either because of the location or reactivity of the nitrene generated on the photoaffinity probe.
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Michaelson DM, Barkai G, Barenholz Y. Asymmetry of lipid organization in cholinergic synaptic vesicle membranes. Biochem J 1983; 211:155-62. [PMID: 6870819 PMCID: PMC1154339 DOI: 10.1042/bj2110155] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The lipid composition of purified Torpedo cholinergic synaptic vesicles was determined and their distribution between the inner and outer leaflets of the vesicular membrane was investigated. The vesicles contain cholesterol and phospholipids at a molar ratio of 0.63. The vesicular phospholipids are (mol% of total phospholipids): phosphatidylcholine (40.9); phosphatidylethanolamine (24.6); plasmenylethanolamine (11.5); sphingomyelin (12); phosphatidylserine (7.3); phosphatidylinositol (3.7). The asymmetry of the synaptic vesicle membranes was investigated by two independent approaches: (a) determining accessibility of the amino lipids to the chemical label trinitrobenzenesulphonic acid (TNBS); (b) determining accessibility of the vesicular glycerophospholipids to phospholipase C (Bacillus cereus). TNBS was found to render the vesicles leaky and thus cannot be used reliably to determine the asymmetry of Torpedo synaptic vesicle membranes. Incubation of the vesicles with phospholipase C (Bacillus cereus) results in biphasic hydrolysis of the vesicular glycerophospholipids. About 45% of the phospholipids are hydrolysed in less than 1 min, during which no vesicular acetylcholine is released. In the second phase, the hydrolysis of the phospholipids slows down markedly and is accompanied by loss of all the vesicular acetylcholine. These findings suggest that the lipids hydrolysed during the first phase are those comprising the outer leaflet. Analysis of the results thus obtained indicate that the vesicular membrane is asymmetric: all the phosphatidylinositol, 77% of the phosphatidylethanolamine, 47% of the plasmenylethanolamine and 58% of the phosphatidylcholine were found to reside in the outer leaflet. Since phosphatidylserine is a poor substrate for phospholipase C (B. cereus), its distribution between the two leaflets of the synaptic vesicle membrane is only suggestive.
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Higgins JA. The contribution of electron microscopic cytochemistry to an understanding of the biogenesis of the endoplasmic reticulum of rat hepatocytes. J Microsc 1982; 128:57-67. [PMID: 7143436 DOI: 10.1111/j.1365-2818.1982.tb00437.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The endoplasmic reticulum has the enzymic machinery for the synthesis of both protein and phospholipid and hence plays a central role in its own biogenesis and that of other cellular membranes. The evidence available concerning the biogenesis of the phospholipid bilayer of the endoplasmic reticulum, particularly from the application of the structural cytochemical methods for the localization of acyltransferases, is reviewed. The observations are consistent with a model in which phospholipid is synthesized in situ at the site of membrane growth. Synthesis is asymmetric, with most enzymes located at the cytoplasmic side of the membrane, and controlled transmembrane movement of phospholipid results in an asymmetric bilayer.
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Chap H, Perret B, Mauco G, Plantavid M, Laffont F, Simon MF, Douste-Blazy L. Organization and role of platelet membrane phospholipids as studied with phospholipases A2 from various venoms and phospholipases C from bacterial origin. Toxicon 1982; 20:291-8. [PMID: 7080042 DOI: 10.1016/0041-0101(82)90229-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Phospholipases A2 from various snake or bee venoms and phospholipases C secreted as exotoxins by several bacteria have been used to study the transverse distribution of phospholipids in the platelet plasma membrane and their role in platelet activation. An asymmetric distribution was described for phospholipids, characterized by a preferential localization of sphingomyelin and phosphatidylcholine in plasma membrane outer leaflet, whereas the inner half contains almost all of the anionic procoagulant phosphatidylserine and phosphatidylinositol. Such a distribution might explain the latency of procoagulant activity in resting platelets and implies an intracellular localization of arachidonic acid, the precursor of prostaglandins and thromboxanes. The external arachidonic acid is involved in phospholipase A2-induced aggregation, whereas phospholipase C from Clostridium welchii stimulates platelets through a thromboxane-independent pathway. The latter one is directly linked to the formation of phosphatidic and lysophosphatidic acids, which are able to activate cells through calcium mobilization. So, phospholipase C represents an interesting tool for studying the biochemical processes accompanying stimulation, since it is shown that it mimics the effects of an intracellular phospholipase C, the role of which in platelet activation is discussed.
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