1
|
Bakshi T, Pham D, Kaur R, Sun B. Hidden Relationships between N-Glycosylation and Disulfide Bonds in Individual Proteins. Int J Mol Sci 2022; 23:ijms23073742. [PMID: 35409101 PMCID: PMC8998389 DOI: 10.3390/ijms23073742] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/25/2022] [Accepted: 03/28/2022] [Indexed: 02/04/2023] Open
Abstract
N-Glycosylation (NG) and disulfide bonds (DBs) are two prevalent co/post-translational modifications (PTMs) that are often conserved and coexist in membrane and secreted proteins involved in a large number of diseases. Both in the past and in recent times, the enzymes and chaperones regulating these PTMs have been constantly discovered to directly interact with each other or colocalize in the ER. However, beyond a few model proteins, how such cooperation affects N-glycan modification and disulfide bonding at selective sites in individual proteins is largely unknown. Here, we reviewed the literature to discover the current status in understanding the relationships between NG and DBs in individual proteins. Our results showed that more than 2700 human proteins carry both PTMs, and fewer than 2% of them have been investigated in the associations between NG and DBs. We summarized both these proteins with the reported relationships in the two PTMs and the tools used to discover the relationships. We hope that, by exposing this largely understudied field, more investigations can be encouraged to unveil the hidden relationships of NG and DBs in the majority of membranes and secreted proteins for pathophysiological understanding and biotherapeutic development.
Collapse
Affiliation(s)
- Tania Bakshi
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
| | - David Pham
- Department of Computing Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
| | - Raminderjeet Kaur
- Faculty of Health Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
| | - Bingyun Sun
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
- Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
- Correspondence:
| |
Collapse
|
2
|
Cao X, Zheng Y, Wu S, Yang N, Wu J, Liu B, Ye W, Yang M, Yue X. Characterization and comparison of milk fat globule membrane N-glycoproteomes from human and bovine colostrum and mature milk. Food Funct 2019; 10:5046-5058. [PMID: 31359016 DOI: 10.1039/c9fo00686a] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Human and bovine milk fat globule membrane (MFGM) proteins have been identified and characterized; however, their glycosylation during lactation remains unclear. We adopted a glycoproteomics approach to profile and compare MFGM N-glycoproteomes in human and bovine milk during lactation. A total of 843, 718, 614, and 273 N-glycosite peptides corresponding to 465, 423, 334, and 176 glycoproteins were identified in human colostrum, human mature milk, bovine colostrum, and bovine mature milk, respectively. The biological functions of these MFGM N-glycoproteins were revealed through bioinformatics. Substantial differences were observed between human and bovine milk, and immune-related MFGM N-glycoproteins varied between colostrum and mature milk from both species. Our results expand current knowledge of MFGM N-glycoproteomes, and further demonstrate the complexity and biological functions of MFGM N-glycosylation. These data can provide references for the application of bovine MFGM N-glycoproteins in infant formula to resemble human milk and in functional foods.
Collapse
Affiliation(s)
- Xueyan Cao
- College of Food Science, Shenyang Agricultural University, Shenyang 110866, PR China.
| | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Yu Q, Wang B, Chen Z, Urabe G, Glover MS, Shi X, Guo LW, Kent KC, Li L. Electron-Transfer/Higher-Energy Collision Dissociation (EThcD)-Enabled Intact Glycopeptide/Glycoproteome Characterization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1751-1764. [PMID: 28695533 PMCID: PMC5711575 DOI: 10.1007/s13361-017-1701-4] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/28/2017] [Accepted: 04/29/2017] [Indexed: 05/04/2023]
Abstract
Protein glycosylation, one of the most heterogeneous post-translational modifications, can play a major role in cellular signal transduction and disease progression. Traditional mass spectrometry (MS)-based large-scale glycoprotein sequencing studies heavily rely on identifying enzymatically released glycans and their original peptide backbone separately, as there is no efficient fragmentation method to produce unbiased glycan and peptide product ions simultaneously in a single spectrum, and that can be conveniently applied to high throughput glycoproteome characterization, especially for N-glycopeptides, which can have much more branched glycan side chains than relatively less complex O-linked glycans. In this study, a redefined electron-transfer/higher-energy collision dissociation (EThcD) fragmentation scheme is applied to incorporate both glycan and peptide fragments in one single spectrum, enabling complete information to be gathered and great microheterogeneity details to be revealed. Fetuin was first utilized to prove the applicability with 19 glycopeptides and corresponding five glycosylation sites identified. Subsequent experiments tested its utility for human plasma N-glycoproteins. Large-scale studies explored N-glycoproteomics in rat carotid arteries over the course of restenosis progression to investigate the potential role of glycosylation. The integrated fragmentation scheme provides a powerful tool for the analysis of intact N-glycopeptides and N-glycoproteomics. We also anticipate this approach can be readily applied to large-scale O-glycoproteome characterization. Graphical Abstract ᅟ.
Collapse
Affiliation(s)
- Qing Yu
- School of Pharmacy, University of Wisconsin, Madison, WI, 53705, USA
| | - Bowen Wang
- Department of Surgery, Wisconsin Institutes for Medical Research, Madison, WI, 53705, USA
| | - Zhengwei Chen
- Department of Chemistry, University of Wisconsin, Madison, WI, 53706, USA
| | - Go Urabe
- Department of Surgery, Wisconsin Institutes for Medical Research, Madison, WI, 53705, USA
| | - Matthew S Glover
- School of Pharmacy, University of Wisconsin, Madison, WI, 53705, USA
- Cardiovascular Research Center Training Program in Translational Cardiovascular Science, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Xudong Shi
- Department of Surgery, Wisconsin Institutes for Medical Research, Madison, WI, 53705, USA
| | - Lian-Wang Guo
- Department of Surgery, Wisconsin Institutes for Medical Research, Madison, WI, 53705, USA
| | - K Craig Kent
- The Ohio State University Wexner Medical Center, Columbus, OH, 43210, USA
| | - Lingjun Li
- School of Pharmacy, University of Wisconsin, Madison, WI, 53705, USA.
- Department of Chemistry, University of Wisconsin, Madison, WI, 53706, USA.
- Cardiovascular Research Center Training Program in Translational Cardiovascular Science, University of Wisconsin-Madison, Madison, WI, 53705, USA.
| |
Collapse
|
4
|
Hirano M, Totani K, Fukuda T, Gu J, Suzuki A. N-Glycoform-dependent interactions of megalin with its ligands. Biochim Biophys Acta Gen Subj 2017; 1861:3106-3118. [DOI: 10.1016/j.bbagen.2016.10.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 09/30/2016] [Accepted: 10/19/2016] [Indexed: 12/18/2022]
|
5
|
Emonard H, Théret L, Bennasroune AH, Dedieu S. Regulation of LRP-1 expression: make the point. ACTA ACUST UNITED AC 2014; 62:84-90. [PMID: 24661974 DOI: 10.1016/j.patbio.2014.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 02/14/2014] [Indexed: 12/14/2022]
Abstract
The low-density lipoprotein receptor-related protein-1 (LRP-1) is a membrane receptor displaying both scavenging and signaling functions. The wide variety of extracellular ligands and of cytoplasmic scaffolding and signaling proteins interacting with LRP-1 gives it a major role not only in physiological processes, such as embryogenesis and development, but also in critical pathological situations, including cancer and neurological disorders. In this review, we describe the molecular mechanisms involved at distinct levels in the regulation of LRP-1, from its expression to the proper location and stability at the cell surface.
Collapse
Affiliation(s)
- H Emonard
- UMR CNRS 7369, unité MEDyC (matrice extracellulaire et dynamique cellulaire), université de Reims-Champagne-Ardenne (URCA), UFR sciences exactes et naturelles, campus Moulin-de-la-Housse, BP 1039, 51687 Reims cedex 2, France
| | - L Théret
- UMR CNRS 7369, unité MEDyC (matrice extracellulaire et dynamique cellulaire), université de Reims-Champagne-Ardenne (URCA), UFR sciences exactes et naturelles, campus Moulin-de-la-Housse, BP 1039, 51687 Reims cedex 2, France
| | - A H Bennasroune
- UMR CNRS 7369, unité MEDyC (matrice extracellulaire et dynamique cellulaire), université de Reims-Champagne-Ardenne (URCA), UFR sciences exactes et naturelles, campus Moulin-de-la-Housse, BP 1039, 51687 Reims cedex 2, France
| | - S Dedieu
- UMR CNRS 7369, unité MEDyC (matrice extracellulaire et dynamique cellulaire), université de Reims-Champagne-Ardenne (URCA), UFR sciences exactes et naturelles, campus Moulin-de-la-Housse, BP 1039, 51687 Reims cedex 2, France.
| |
Collapse
|
6
|
Lu D, Yang C, Liu Z. How hydrophobicity and the glycosylation site of glycans affect protein folding and stability: a molecular dynamics simulation. J Phys Chem B 2011; 116:390-400. [PMID: 22118044 DOI: 10.1021/jp203926r] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Glycosylation is one of the most common post-translational modifications in the biosynthesis of protein, but its effect on the protein conformational transitions underpinning folding and stabilization is poorly understood. In this study, we present a coarse-grained off-lattice 46-β barrel model protein glycosylated by glycans with different hydrophobicity and glycosylation sites to examine the effect of glycans on protein folding and stabilization using a Langevin dynamics simulation, in which an H term was proposed as the index of the hydrophobicity of glycan. Compared with its native counterpart, introducing glycans of suitable hydrophobicity (0.1 < H < 0.4) at flexible peptide residues of this model protein not only facilitated folding of the protein but also increased its conformation stability significantly. On the contrary, when glycans were introduced at the restricted peptide residues of the protein, only those hydrophilic (H = 0) or very weak hydrophobic (H < 0.2) ones contributed slightly to protein stability but hindered protein folding due to increased free energy barriers. The glycosylated protein retained the two-step folding mechanism in terms of hydrophobic collapse and structural rearrangement. Glycan chains located in a suitable site with an appropriate hydrophobicity facilitated both collapse and rearrangement, whereas others, though accelerating collapse, hindered rearrangement. In addition to entropy effects, that is, narrowing the space of the conformations of the unfolded state, the presence of glycans with suitable hydrophobicity at suitable glycosylation site strengthened the folded state via hydrophobic interaction, that is, the enthalpy effect. The simulations have shown both the stabilization and the destabilization effects of glycosylation, as experimentally reported in the literature, and provided molecular insight into glycosylated proteins. The understanding of the effects of glycans with different hydrophobicities on the folding and stability of protein, as attempted by the present work, is helpful not only to explain the stabilization and destabilization effect of real glycoproteins but also to design protein-polymer conjugates for biotechnological purposes.
Collapse
Affiliation(s)
- Diannan Lu
- Department of Chemical Engineering, Tsinghua University, Beijing, China
| | | | | |
Collapse
|
7
|
Wang D, Zaitsev S, Taylor G, d’Azzo A, Bonten E. Protective protein/cathepsin A rescues N-glycosylation defects in neuraminidase-1. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1790:275-82. [PMID: 19714866 PMCID: PMC2888680 DOI: 10.1016/j.bbagen.2009.01.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND Neuraminidase-1 (NEU1) catabolizes the hydrolysis of sialic acids from sialo-glycoconjugates. NEU1 depends on its interaction with the protective protein/cathepsin A (PPCA) for lysosomal compartmentalization and catalytic activation. Murine NEU1 contains 4 N-glycosylation sites, 3 of which are conserved in the human enzyme. The expression of NEU1 gives rise to differentially glycosylated proteins. METHODS We generated single-point mutations in mouse NEU1 at each of the 4 N-glycosylation sites. Mutant enzymes were expressed in NEU1-deficient cells in the presence and absence of PPCA. RESULTS All 4 N-glycosylation variants were targeted to the lysosomal/endosomal compartment. All N-glycans, with the exception of the most C-terminal glycan, were important for maintaining stability or catalytic activity. The loss of catalytic activity caused by the deletion of the second N-glycan was rescued by increasing PPCA expression. Similar results were obtained with a human NEU1 N-glycosylation mutant identified in a sialidosis patient. The N-terminal N-glycan of NEU1 is indispensable for its function, whereas the C-terminal N-glycan appears to be non-essential. The omission of the second N-glycan can be compensated for by upregulating the expression of PPCA. GENERAL SIGNIFICANCE These findings could be relevant for the design of target therapies for patients carrying specific NEU1 mutations.
Collapse
Affiliation(s)
- Dongning Wang
- Department of Genetics and Tumor Cell Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105-2794, USA
| | - Slava Zaitsev
- Centre for Biomolecular Sciences, University of St Andrews, St Andrews, Fife KY16 9UA, Scotland
| | - Garry Taylor
- Centre for Biomolecular Sciences, University of St Andrews, St Andrews, Fife KY16 9UA, Scotland
| | - Alessandra d’Azzo
- Department of Genetics and Tumor Cell Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105-2794, USA
| | - Erik Bonten
- Department of Genetics and Tumor Cell Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105-2794, USA
| |
Collapse
|
8
|
Lee SH, Takahashi M, Honke K, Miyoshi E, Osumi D, Sakiyama H, Ekuni A, Wang X, Inoue S, Gu J, Kadomatsu K, Taniguchi N. Loss of core fucosylation of low-density lipoprotein receptor-related protein-1 impairs its function, leading to the upregulation of serum levels of insulin-like growth factor-binding protein 3 in Fut8-/- mice. J Biochem 2007; 139:391-8. [PMID: 16567404 DOI: 10.1093/jb/mvj039] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
alpha1,6-Fucosyltransferase (Fut8) catalyzes the transfer of a fucose residue from GDP-fucose to the innermost N-acetylglucosamine residue of N-glycans. Here we report that the loss of core fucosylation impairs the function of low-density lipoprotein (LDL) receptor-related protein-1 (LRP-1), a multifunctional scavenger and signaling receptor, resulting in a reduction in the endocytosis of insulin like growth factor (IGF)-binding protein-3 (IGFBP-3) in the cells derived from Fut8-null (Fut8-/-) mice. The reduced endocytosis was restored by the re-introduction of Fut8. Serum levels of IGFBP-3 were markedly upregulated in Fut8-/- mice. These data clearly indicate that core fucosylation is crucial for the scavenging activity of LRP-1 in vivo.
Collapse
Affiliation(s)
- Seung Ho Lee
- Department of Biochemistry, Osaka University Graduate School of Medicine, B1, 2-2 Yamadaoka, Suita, Osaka 565-0871
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
How sugars convey information on protein conformation in the endoplasmic reticulum. Semin Cell Dev Biol 2007; 18:732-42. [PMID: 17997334 DOI: 10.1016/j.semcdb.2007.09.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 07/24/2007] [Accepted: 09/05/2007] [Indexed: 11/21/2022]
Abstract
The N-glycan-dependent quality control of glycoprotein folding prevents endoplasmic reticulum to Golgi exit of folding intermediates, irreparably misfolded glycoproteins and not completely assembled multimeric complexes. It also enhances folding efficiency by preventing aggregation and facilitating formation of proper disulfide bonds. The control mechanism essentially involves four components, resident lectin-chaperones that recognize monoglucosylated polymannose glycans, a lectin-associated oxidoreductase acting on monoglucosylated glycoproteins, a glucosyltransferase and a glucosidase that creates monoglucosylated epitopes in glycans transferred in protein N-glycosylation or removes the glucose units added by the glucosyltransferase. This last enzyme is the only mechanism component sensing glycoprotein conformations as it creates monoglucosylated glycans exclusively in not properly folded species or in not completely assembled complexes. The purpose of the review is to describe the most significant recent findings on the mechanism of glycoprotein folding and assembly quality control and to discuss the main still unanswered questions.
Collapse
|
10
|
Abstract
The biosynthesis and export of LDL receptor-related proteins rely on specialized chaperones in the endoplasmic reticulum. Two recent papers in Molecular Cell by Fisher et al. (2006) and Lee et al. (2006) reveal a novel mechanism by which one of these chaperones, the receptor-associated protein RAP, accomplishes this task.
Collapse
Affiliation(s)
- Joachim Herz
- Department of Molecular Genetics, University of Texas Southwestern, Dallas, Texas 75390, USA.
| |
Collapse
|
11
|
Contreras-Alcantara S, Godby JA, Delos SE. The Single Ligand-binding Repeat of Tva, a Low Density Lipoprotein Receptor-related Protein, Contains Two Ligand-binding Surfaces. J Biol Chem 2006; 281:22827-38. [PMID: 16769730 DOI: 10.1074/jbc.m512599200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The receptor for avian sarcoma/leukosis virus subtype A (ASLV-A), Tva, is the simplest member of the low density lipoprotein receptor family containing a single ligand-binding repeat (LBR). Most LBRs contain a central Trp (Trp33 in Tva) that is important for ligand binding and, for the low density lipoprotein receptor, is associated with familial hypercholesterolemia. The Tva ligand-binding module contains a second Trp (Trp48) that is part of a DEW motif present in a subset of LBRs. Trp48 is important for ASLV-A infectivity. A soluble Tva (sTva) ligand-binding module is sufficient for ASLV-A infectivity. Tva interacts with the viral glycoprotein, and a soluble receptor-binding domain (SUA) binds sTva with picomolar affinity. We investigated whether Tva, a retroviral receptor, could behave as a classic LBR by assessing sTva interactions with the universal receptor-associated protein (RAP) and comparing these interactions with those between sTva and its viral ligand (SUA). To address the role of the two Trp residues in Tva function, we prepared sTva harboring mutations of Trp33, Trp48, or both and determined the binding kinetics with RAP and SUA. We found that sTva behaved as a "normal" receptor toward RAP, requiring both calcium and Trp33 for binding. However, sTva binding to SUA required neither calcium nor Trp33. Furthermore, sTva could bind both RAP and SUA simultaneously. These results show that the single LBR of Tva has two ligand-binding sites, raising the possibility that other LBRs may also.
Collapse
|
12
|
Ellerman DA, Myles DG, Primakoff P. A Role for Sperm Surface Protein Disulfide Isomerase Activity in Gamete Fusion: Evidence for the Participation of ERp57. Dev Cell 2006; 10:831-7. [PMID: 16740484 DOI: 10.1016/j.devcel.2006.03.011] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 03/02/2006] [Accepted: 03/28/2006] [Indexed: 11/16/2022]
Abstract
In mammals, sperm-egg interaction is based on molecular events either unique to gametes or also present in somatic cells. In gamete fusion, it is unknown which features are gamete specific and which are shared with other systems. Conformational changes mediated by thiol-disulfide exchange are involved in the activation of some virus membrane fusion proteins. Here we asked whether that mechanism is also operative in sperm-egg fusion. Different inhibitors of protein disulfide isomerase (PDI) activity were able to inhibit sperm-egg fusion in vitro. While pretreatment of oocytes had no effect, pretreatment of sperm reduced their fusion ability. Some members of the PDI family were detected on the sperm head, and use of specific antibodies and substrates suggested that the oxidoreductase ERp57 has a role in gamete fusion. The results support the idea that thiol-disulfide exchange is a mechanism that may act in gamete fusion to produce conformational changes in fusion-active proteins.
Collapse
Affiliation(s)
- Diego A Ellerman
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, Davis, California 95616, USA.
| | | | | |
Collapse
|
13
|
Abstract
We identified 1113 articles (103 reviews, 1010 primary research articles) published in 2005 that describe experiments performed using commercially available optical biosensors. While this number of publications is impressive, we find that the quality of the biosensor work in these articles is often pretty poor. It is a little disappointing that there appears to be only a small set of researchers who know how to properly perform, analyze, and present biosensor data. To help focus the field, we spotlight work published by 10 research groups that exemplify the quality of data one should expect to see from a biosensor experiment. Also, in an effort to raise awareness of the common problems in the biosensor field, we provide side-by-side examples of good and bad data sets from the 2005 literature.
Collapse
Affiliation(s)
- Rebecca L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
| | | |
Collapse
|
14
|
Okudo H, Kato H, Arakaki Y, Urade R. Cooperation of ER-60 and BiP in the Oxidative Refolding of Denatured Proteins In Vitro. ACTA ACUST UNITED AC 2005; 138:773-80. [PMID: 16428306 DOI: 10.1093/jb/mvi166] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
ER-60 is a PDI family protein that has protein thiol-disulfide oxidoreductase activity. It has been shown to associate with BiP in the endoplasmic reticulum. Here, we analyzed the cooperation of ER-60 and BiP in the oxidative refolding of denatured proteins in vitro. ER-60 facilitated the refolding of 20 or 30% of denatured alpha-lactalbumin or ribonuclease B during incubation for 80 min, and these levels of nearly doubled on the addition of BiP to the reaction mixture. BiP alone could not refold denatured ribonuclease B, but could refold denatured alpha-lactalbumin a little. Enhancement of oxidative refolding of alpha-lactalbumin by ER-60 could be detected only when ER-60 was present from the start of refolding. On surface plasmon resonance analysis, ER-60 was shown to associate with BiP. The association was not influenced by ATP or ADP. Domains a and/or b' of ER-60 were implicated in the association with BiP.
Collapse
Affiliation(s)
- Hirokazu Okudo
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto 611-0011
| | | | | | | |
Collapse
|