1
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North RA. Serendipity in senescence. FUNCTION (OXFORD, ENGLAND) 2022; 4:zqac064. [PMID: 36606243 PMCID: PMC9809900 DOI: 10.1093/function/zqac064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 12/04/2022] [Accepted: 12/15/2022] [Indexed: 12/25/2022]
Affiliation(s)
- R A North
- Address correspondence to R. A. N. (E-mail: )
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2
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CATs, a family of three distinct mammalian cationic amino acid transporters. Amino Acids 2013; 11:193-208. [PMID: 24178687 DOI: 10.1007/bf00813860] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/1996] [Accepted: 04/05/1996] [Indexed: 09/29/2022]
Abstract
Three related mammalian carrier proteins that mediate the transport of cationic amino acids through the plasma membrane have been identified in murine and human cells (CAT for cationic amino acid transporter). Models of the CAT proteins in the membrane suggest they have 12 or 14 transmembrane domains connected by short hydrophilic loops and intracellular N- and C-termini. The transport activity of the CAT proteins is sensitive to trans-stimulation and independent of the presence of sodium ions. These features agree with the behaviour of carrier proteins mediating facilitated diffusion. The three CAT proteins, CAT-1, CAT-2A and CAT-2(B) are encoded by two different genes (CAT-1 and CAT-2). CAT-1 and CAT-2(B) exhibit transport properties consistent with system y(+), the principal mechanism for cellular uptake of cationic amino acids. In contrast, CAT-2A has tenfold lower substrate affinity, greater apparent maximal velocity and it is much less sensitive to trans-stimulation. In addition to structural and functional aspects, this review discusses the role of the CAT proteins for supplying substrate to NO synthases and the property of the rodent CAT-1 proteins to function as virus receptors.
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3
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Akerud H, Ronquist G, Wiberg-Itzel E. Lactate distribution in culture medium of human myometrial biopsies incubated under different conditions. Am J Physiol Endocrinol Metab 2009; 297:E1414-9. [PMID: 19826101 DOI: 10.1152/ajpendo.00458.2009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is generally believed that a relationship exists between muscle fatigue and intracellular accumulation of lactate. This reasoning is relevant to obstetrical issues. Myocytes in uterus work together during labor, and the contractions need to be strong and synchronized for a child to be delivered. At labor dystocia, the progress of labor becomes slow or arrested after a normal beginning. It has been described that, during labor dystocia, when the force of the contractions is low, the uterus is under hypoxia, and anaerobic conditions with high levels of lactate in amniotic fluid dominate. The purpose of this study was to examine whether myometrial cells are involved in the production of lactate in amniotic fluid and whether there are differences in production and distribution of lactate in cells incubated under aerobic and anaerobic conditions. We also wanted to elucidate the involvement of specific membrane-bound lactate carriers. Women undergoing elective caesarean section were included. Myometrial biopsies from uteri were collected and subjected to either immunohistochemistry to identify lactate carriers or in vitro experiments to analyze production of lactate. The presence of lactate carriers named monocarboxylate transporters 1 and 4 was verified. Myometrial cells produced lactate extracellularly, and the lactate carriers operated differently under anaerobic and aerobic conditions; while being mainly unidirectional under anaerobic conditions, they became bidirectional under aerobic conditions. Human myometrial cells produced and delivered lactate to the extracellular medium under both anaerobic and aerobic conditions. The delivery was mediated by lactate carriers.
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Affiliation(s)
- Helena Akerud
- Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden.
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4
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Abstract
L-Arginine (L-Arg) is a basic amino acid that plays a central role in the biosynthesis of nitric oxide, creatine, agmantine, polyamines, proline and glutamate. Most tissues, including myocardium, must import L-Arg from the circulation to ensure adequate intracellular levels of this amino acid. This study reports novel L-Arg-activated inward currents in whole-cell voltage-clamped rat ventricular cardiomyocytes. Ion-substitution experiments identified extracellular L-Arg as the charge-carrying cationic species responsible for these currents, which, thus, represent L-Arg import into cardiac myocytes. This result was independently confirmed by an increase in myocyte nitric oxide production upon extracellular application of L-Arg. The inward movement of Arg molecules was found to be passive and independent of Na(2+), K(2+), Ca(2+) and Mg(2+). The process displayed saturation and membrane potential (V(m))-dependent kinetics, with a K(0.5) for l-Arg that increased from 5 mm at hyperpolarizing V(m) to 20 mm at +40 mV. L-Lysine and L-ornithine but not D-Arg produced currents with characteristics similar to that activated by L-Arg indicating that the transport process is stereospecific for cationic L-amino acids. L-Arg current was fully blocked after brief incubation with 0.2 mm N-ethylmaleimide. These features suggest that the activity of the low-affinity, high-capacity CAT-2A member of the y(2+) family of transporters is responsible for L-Arg currents in acutely isolated cardiomyocytes. Regardless of the mechanism, we hypothesize that a low-affinity arginine transport process in heart, by ensuring substrate availability for sustained NO production, might play a cardio-protective role during catabolic states known to increase Arg plasma levels severalfold.
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Affiliation(s)
- R Daniel Peluffo
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, PO Box 1709, Newark, NJ 07101-1709, USA.
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5
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Christensen HN. Some special kinetic problems of transport. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 32:1-20. [PMID: 4892501 DOI: 10.1002/9780470122778.ch1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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6
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Sharpe JG, Seidel ER. Polyamines are absorbed through a y+ amino acid carrier in rat intestinal epithelial cells. Amino Acids 2005; 29:245-53. [PMID: 16133764 DOI: 10.1007/s00726-005-0234-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Accepted: 05/20/2005] [Indexed: 10/25/2022]
Abstract
Due to the similarity in transport characteristics of polyamines and the y+ basic amino acid system, we hypothesized that both substrates could be moving through a common carrier site. Competitive and cross inhibition experiments in intestinal epithelial cells revealed the possibility of a common transport site. N-ethylmalemide (NEM) inhibited both lysine and putrescine transport, confirming that both were carried by a y+ transporter. Overexpressing the y+ transporter CAT-1 in a polyamine transport-deficient cell line, CHO-MG, did not reconstitute polyamine-transport. Thus, polyamines are not traveling through CAT-1. To determine if lysine is carried by a polyamine transport site, an antizyme-overexpressing cell line was used. Antizyme overexpression decreased polyamine uptake by 50%; in contrast, lysine transport was unaffected. Therefore, lysine is not traveling through a polyamine transport site. It appears that polyamines and lysine are likely traveling through a common unknown y+ transport site.
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Affiliation(s)
- J G Sharpe
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, North Carolina 27858, USA
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7
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Nawrath H, Wegener JW, Rupp J, Habermeier A, Closs EI. Voltage dependence of L-arginine transport by hCAT-2A and hCAT-2B expressed in oocytes from Xenopus laevis. Am J Physiol Cell Physiol 2000; 279:C1336-44. [PMID: 11029280 DOI: 10.1152/ajpcell.2000.279.5.c1336] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Membrane potential and currents were investigated with the two-electrode voltage-clamp technique in Xenopus laevis oocytes expressing hCAT-2A or hCAT-2B, the splice variants of the human cationic amino acid transporter hCAT-2. Both hCAT-2A- and hCAT-2B-expressing oocytes exhibited a negative extracellular L-arginine concentration ([L-Arg](o))-sensitive membrane potential, additive to the K(+) diffusion potential, when cells were incubated in Leibovitz medium (containing 1.45 mM L-Arg and 0.25 mM L-lysine). The two carrier proteins produced inward and outward currents, which were dependent on the L-Arg gradient and membrane potential. Ion substitution experiments showed that the hCAT-induced currents were independent of external Na(+), K(+), Ca(2+), or Mg(2+). The apparent Michaelis-Menten constant values at -60 mV, obtained from plots of L-Arg-induced currents against [L-Arg](o), were 0.97 and 0.13 mM in oocytes expressing hCAT-2A and hCAT-2B, respectively; maximal currents amounted to -194 +/- 8 and -84 +/- 2 nA, respectively. At saturating [L-Arg](o), the current-voltage relationships of hCAT-2A-expressing oocytes became steeper, yielding an additional conductance up to 2 microS/oocyte, whereas those of hCAT-2B-expressing oocytes were simply shifted to the right, resulting in voltage-independent difference currents. The distinct electrochemical properties of the two isoforms of hCAT-2 are assumed to contribute differentially to the membrane transport and the maintenance of cationic amino acids in various tissues.
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Affiliation(s)
- H Nawrath
- Department of Pharmacology, Johannes Gutenberg University, 55101 Mainz, Germany.
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8
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Devés R, Boyd CA. Transporters for cationic amino acids in animal cells: discovery, structure, and function. Physiol Rev 1998; 78:487-545. [PMID: 9562037 DOI: 10.1152/physrev.1998.78.2.487] [Citation(s) in RCA: 346] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The structure and function of the four cationic amino acid transporters identified in animal cells are discussed. The systems differ in specificity, cation dependence, and physiological role. One of them, system y+, is selective for cationic amino acids, whereas the others (B[0,+], b[0,+], and y+ L) also accept neutral amino acids. In recent years, cDNA clones related to these activities have been isolated. Thus two families of proteins have been identified: 1) CAT or cationic amino acid transporters and 2) BAT or broad-scope transport proteins. In the CAT family, three genes encode for four different isoforms [CAT-1, CAT-2A, CAT-2(B) and CAT-3]; these are approximately 70-kDa proteins with multiple transmembrane segments (12-14), and despite their structural similarity, they differ in tissue distribution, kinetics, and regulatory properties. System y+ is the expression of the activity of CAT transporters. The BAT family includes two isoforms (rBAT and 4F2hc); these are 59- to 78-kDa proteins with one to four membrane-spanning segments, and it has been proposed that these proteins act as transport regulators. The expression of rBAT and 4F2hc induces system b[0,+] and system y+ L activity in Xenopus laevis oocytes, respectively. The roles of these transporters in nutrition, endocrinology, nitric oxide biology, and immunology, as well as in the genetic diseases cystinuria and lysinuric protein intolerance, are reviewed. Experimental strategies, which can be used in the kinetic characterization of coexpressed transporters, are also discussed.
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Affiliation(s)
- R Devés
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago
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9
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Crawford DH, Chen S, Boyd CA. Cationic amino acid transport in human T lymphocytes is markedly increased in the CD45RA, CD8+ population after activation. Immunology 1994; 82:357-60. [PMID: 7959867 PMCID: PMC1414877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Membrane transport of cationic amino acids is essential for cells which are actively metabolizing L-arginine or L-lysine. In human cells most of this transport occurs through y+, a transport system which is only now being characterized at the molecular level. We have previously shown that phytohaemagglutinin (PHA) stimulation of peripheral blood E rosette positive (T) lymphocytes specifically activated lysine transport through system y+, whereas Staphlyococcus aureus Cowan A (SAC) stimulation of the E rosette negative fraction did not. We have now analysed this effect in PHA-activated CD4, CD8, CD45RO and CD45RA T-cell subsets. Both PHA-activated CD4+ and CD8+ T cells have increased lysine transport through y+, and in seven out of eight experiments, more activity was seen in the CD8+ fraction. In contrast, marked differences in y+ activity were seen between the PHA-activated CD45RO and CD45RA subsets. Thus in six experiments y+ activity was markedly increased in the CD45RA (naive T cell) population but not in the CD45RO (memory) cells. In one further experiment the activated CD45RO, CD4- population (enriched for CD45RA+, CD8+) was studied and y+ activity was shown to be maximal in this cell subset. Transport of arginine is essential for nitric oxide synthesis. Our findings therefore suggest that activated CD45RA, CD8+ T cells are capable of nitric oxide production.
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Affiliation(s)
- D H Crawford
- Department of Clinical Sciences, London School of Hygiene and Tropical Medicine, U.K
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10
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Kavanaugh M, Wang H, Zhang Z, Zhang W, Wu Y, Dechant E, North R, Kabat D. Control of cationic amino acid transport and retroviral receptor functions in a membrane protein family. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)40699-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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11
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Devés R, Chavez P, Boyd CA. Identification of a new transport system (y+L) in human erythrocytes that recognizes lysine and leucine with high affinity. J Physiol 1992; 454:491-501. [PMID: 1474499 PMCID: PMC1175616 DOI: 10.1113/jphysiol.1992.sp019275] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
1. The effect of neutral amino acids on the transport of L-lysine across the human erythrocyte membrane was studied. 2. All neutral amino acids tested (range 0.3-5 mM) inhibit the influx of L-[14C]lysine (1 microM). The inhibition pattern is biphasic, and tends to reach a maximum at approximately 50% of the original flux. The concentrations that give 25% inhibition are (mM): L-cysteine (2.7), L-alanine (1.3), L-serine (0.9), L-isoleucine (0.6), L-phenylalanine (0.35), L-methionine (< 0.3), L-leucine (< 0.3). L-lysine and L-arginine completely inhibit the rate at the highest concentration. 3. These results can be explained by assuming that L-lysine transport occurs through two independent transporters that differ in their affinity for neutral amino acids. A detailed kinetic analysis of the effect of L-leucine on L-lysine entry is consistent with this hypothesis. 4. Using a new experimental strategy, the substrate and inhibitor transport parameters for the two systems were determined. The half-saturation constants for lysine (+/- S.E.M.) are found to be: KmA, 0.014 +/- 0.002 mM and KmB, 0.112 +/- 0.017 mM. The maximum rates differ by a factor of 8.2 (VmaxB/VmaxA). The leucine inhibition constants are: KiA, 0.022 +/- 0.003 mM and KiB, 30.36 +/- 7.9 mM. If the sodium in the incubation medium is replaced by potassium, the apparent affinity for leucine (1/KiA) is reduced approximately 30-fold. 5. The maximum inhibition caused by leucine decreases as the lysine concentration is raised, showing that leucine acts upon the higher affinity system. 6. When added to the trans side, L-leucine, L-phenylalanine and L-isoleucine do not cause inhibition, but stimulate the flux by approximately 30%. This indicates that these analogues are also transported. 7. In conclusion, in the concentration range 1-100 microM, lysine crosses the red cell membrane through two distinct transport systems, one of which recognizes both neutral and cationic amino acids with high affinity.
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Affiliation(s)
- R Devés
- Department of Physiology and Biophysics, Faculty of Medicine, University of Chile, Santiago
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12
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Van Winkle LJ, Campione AL, Gorman JM. Na+-independent transport of basic and zwitterionic amino acids in mouse blastocysts by a shared system and by processes which distinguish between these substrates. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69048-9] [Citation(s) in RCA: 123] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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13
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Ahearn GA. Nutrient Transport by the Invertebrate Gut. ADVANCES IN COMPARATIVE AND ENVIRONMENTAL PHYSIOLOGY 1988. [DOI: 10.1007/978-3-642-73375-8_3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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14
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AHEARN GREGORYA. NUTRIENT TRANSPORT BY THE CRUSTACEAN GASTROINTESTINAL TRACT: RECENT ADVANCES WITH VESICLE TECHNIQUES. Biol Rev Camb Philos Soc 1987. [DOI: 10.1111/j.1469-185x.1987.tb00625.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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Effects of Na+, H+, and Cl? on alanine transport by lobster hepatopancreatic brush border membrane vesicles. J Comp Physiol B 1986. [DOI: 10.1007/bf00691040] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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16
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Na+-dependent transport of basic, zwitterionic, and bicyclic amino acids by a broad-scope system in mouse blastocysts. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)38994-9] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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17
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Detection and characterization of carrier-mediated cationic amino acid transport in lysosomes of normal and cystinotic human fibroblasts. Role in therapeutic cystine removal? J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89141-4] [Citation(s) in RCA: 153] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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18
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Cationic amino acid transport into cultured animal cells. II. Transport system barely perceptible in ordinary hepatocytes, but active in hepatoma cell lines. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34743-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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19
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White MF, Gazzola GC, Christensen HN. Cationic amino acid transport into cultured animal cells. I. Influx into cultured human fibroblasts. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34742-2] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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20
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Christensen HN. Metabolite transport at cell membranes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1976; 69:3-12. [PMID: 7927 DOI: 10.1007/978-1-4684-3264-0_1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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21
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Basis of Transport Discrimination of Arginine from Other Basic Amino Acids in Salmonella typhimurium. J Biol Chem 1974. [DOI: 10.1016/s0021-9258(19)42159-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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22
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Linask J, Laties GG. Multiphasic absorption of glucose and 3-o-methyl glucose by aged potato slices. PLANT PHYSIOLOGY 1973; 51:289-94. [PMID: 16658317 PMCID: PMC366252 DOI: 10.1104/pp.51.2.289] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The isotherm for glucose absorption by aged potato (Solanum tuberosum var. Russet Burbank) discs shows four distinct phases in the concentration ranges 1.0 to 75 mum, 75 mum to 1.5 mm, 1.5 to 15 mm, and 15 to 100 mm, respectively. Each segment of the multiphasic isotherm, when plotted reciprocally by the method of Lineweaver and Burk or of Hofstee, without regard for uptake in earlier phases, indicates absorption rate to be a hyperbolic function of concentration. The observations suggest that glucose uptake is carrier-mediated, and that the transport barrier undergoes a series of all-or-none transformations at critical external concentrations, yielding successive new and higher values for the parameters Km and V(max) 3-O-Methyl glucose, a nonmetabolizable analogue of glucose, shows the same multiphasic absorption isotherm, with Km values essentially similar to those for glucose uptake, and V(max) values somewhat lower than those for glucose absorption. Whereas the first three phases of the absorption isotherm are taken to reflect passage across the plasma membrane, the fourth phase may reflect kinetics of glucose or 3-O-methyl glucose transport to the vacuole.
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Affiliation(s)
- J Linask
- Department of Biology and Molecular Biology Institute, University of California, Los Angeles, California 90024
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23
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Ottaway JH. The concentration of asparagine in the tissues of rats treated with growth hormone. Biochem J 1972; 129:503-5. [PMID: 4643336 PMCID: PMC1174103 DOI: 10.1042/bj1290503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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24
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Groth U, Rosenberg LE. Transport of dibasic amino acids, cystine, and tryptophan by cultured human fibroblasts: absence of a defect in cystinuria and Hartnup disease. J Clin Invest 1972; 51:2130-42. [PMID: 5054467 PMCID: PMC292370 DOI: 10.1172/jci107020] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Transport of lysine, arginine, cystine, and tryptophan was studied in cultured skin fibroblasts from normal controls and from patients with cystinuria and Hartnup disease. Each of these amino acids was accumulated against concentration gradients by energy-dependent, saturable mechanisms. Lysine and arginine were each transported by two distinct processes which they shared with each other and with ornithine. In contrast, cystine was taken up by a different transport system with no demonstrable affinity for the dibasic amino acids. The time course and Michaelis-Menten kinetics of lysine and cystine uptake by cells from three cystinuric patients differed in no way from those found in control cells. Similarly, the characteristics of tryptophan uptake by cells from a child with Hartnup disease were identical to those noted in control cells. These findings indicate that the specific transport defects observed in gut and kidney in cystinuria and Hartnup disease are not expressed in cultured human fibroblasts, thus providing additional evidence of the important role that cellular differentiation plays in the regulation of expression of the human genome.
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25
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The effect of certain amino acids on reproduction of encephalomyocarditis virus. Arch Virol 1972. [DOI: 10.1007/bf01268001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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26
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Hampton JR. Arginine transport in the culture form of Trypanosoma cruzi. THE JOURNAL OF PROTOZOOLOGY 1971; 18:701-3. [PMID: 4943764 DOI: 10.1111/j.1550-7408.1971.tb03400.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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27
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28
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Abstract
Membrane transport of beta-alanine, l-alanine, and l-proline was studied in a beta-alanine transaminaseless mutant (strain 67) of Pseudomonas fluorescens. In this mutant beta-alanine is metabolically inert, and it was therefore possible to demonstrate active transport of this substrate in the absence of intracellular catabolism. The permease which catalyzes the uptake of beta-alanine also transports l-proline and l-alanine. This common transport system was distinguished from permeases which transport only l-alanine and only l-proline by competition studies in strain 67 and by studies of transport specificity in a permeaseless mutant (strain 67/4MTR).
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29
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Hampton JR. Lysine uptake in cultured Trypanosoma cruzi: interactions of competitive inhibitors. THE JOURNAL OF PROTOZOOLOGY 1970; 17:597-600. [PMID: 5505361 DOI: 10.1111/j.1550-7408.1970.tb04734.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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30
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31
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Christensen HN, Handlogten ME, Thomas EL. Na plus-facilitated reactions of neutral amino acids with a cationic amino acid transport system. Proc Natl Acad Sci U S A 1969; 63:948-55. [PMID: 5259774 PMCID: PMC223544 DOI: 10.1073/pnas.63.3.948] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The predominant basis for transport interactions between neutral and cationic amino acids in the Ehrlich ascites-tumor cell and the rabbit reticulocyte has been identified as a reaction of the neutral amino acid plus Na(+) with the cationic amino acid transport system. This reaction is revealed both by a Na(+)-dependent transport inhibition by the neutral amino acid, and by mutual flux accelerations whereby the neutral amino acid and Na(+) exchange for the cationic amino acid.
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32
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Christensen HN, Handlogten ME. Reactions of neutral amino acids plus Na(+) with a cationic amino acid transport system. FEBS Lett 1969; 3:14-17. [PMID: 11946956 DOI: 10.1016/0014-5793(69)80084-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- H N. Christensen
- Department of Biological Chemistry, The University of Michigan, Ann Arbor, Michigan, USA
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33
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34
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Identification and Analysis of Multiple Glycine Transport Systems in Isolated Mammalian Renal Tubules. J Biol Chem 1968. [DOI: 10.1016/s0021-9258(18)91905-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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35
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36
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37
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Lajtha A. Transport as control mechanism of cerebral metabolite levels. PROGRESS IN BRAIN RESEARCH 1968; 29:201-18. [PMID: 4898073 DOI: 10.1016/s0079-6123(08)64157-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Neame KD. A comparison of the transport systems for amino acids in brain, intestine, kidney and tumour. PROGRESS IN BRAIN RESEARCH 1968; 29:185-99. [PMID: 4898330 DOI: 10.1016/s0079-6123(08)64156-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
Experiments with slices of human kidney cortex from two control subjects demonstrated two distinct transport systems for lysine (alpha and beta) which differ greatly in affinity and capacity. Both systems were found in kidney from two patients with cystinuria. Studies with rat kidney confirmed these findings. These experiments defined only a single transport system for cystine in kidney from both control and cystinuric subjects.
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Behki RM, Hochster RM. METABOLISM OF AMINO ACIDS IN AGROBACTERIUM TUMEFACIENS: I. UPTAKE OF L-VALINE BY RESTING CELLS. ACTA ACUST UNITED AC 1966. [DOI: 10.1139/o66-168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The characteristics of14C-valine uptake by Agrobacterium tumefaciens are described. Highly significant differences were observed with the non-tumorogenic strain IIBNV6and the tumorogenic strain IIBV7K.Resting cells of strain IIBNV6displayed an amino acid uptake pattern, energy requirement, pool saturation, and substrate specificity typical of bacteria (e.g. Escherichia colt) which have been studied previously. In contrast, cells of the strain IIBV7K exhibited an apparent independence from external energy requirements and showed a non-specific competition by structurally unrelated amino acids for14C-valine uptake.In cells of this tumorogenic strain,14C-valine was metabolized after its uptake from the medium, and the metabolic product was effluxed into the extracellular fluid. This product was identified as α-ketoisovaleric acid. Cells of the strain IIBV7K were unable to accumulate this keto acid, although IIBNV6cells took it up readily.Valine uptake by IIBV7K cells was inhibited by a host of structurally unrelated amino acids, which were able to displace the accumulated valine from these cells.The deamination of valine to α-ketoisovaleric acid appears to be associated with a transaminase-type reaction in cells of the strain IIBV7K. Hydroxylamine inhibited the efflux of the product in this strain, whereas in the non-tumorogenic strain it inhibited14C-valine uptake.
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Inui Y, Christensen HN. Discrimination of single transport systems. The Na plus-sensitive transport of neutral amino acids in the Ehrlich cell. J Gen Physiol 1966; 50:203-24. [PMID: 5971029 PMCID: PMC2225630 DOI: 10.1085/jgp.50.1.203] [Citation(s) in RCA: 153] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Uptake of methionine, alpha-aminoisobutyric acid, and alpha-(methyl-amino)-isobutyric acid has been shown to occur by at least two transport systems, one sensitive and the other insensitive to the Na(+) concentration. For alpha-aminoisobutyric acid and its N-methyl derivative, the Na(+)-insensitive uptake is not concentrative and its rate increases almost linearly with concentration within the range examined. In contrast, the Na(+)-insensitive uptake of methionine is concentrative and subject to inhibition by such amino acids as phenylalanine, leucine, and valine, although not in a manner to indicate that the uptake is mediated by a single agency. This component is not produced by a residual operation of the Na(+)-requiring transport system, handicapped by the absence of Na(+) or by its having combined with alpha-aminoisobutyric acid. The increase in the rate of methionine uptake is linear with concentration only above about 16 mM methionine. The Na(+)-sensitive uptakes of methionine, alpha-aminoisobutyric, and alpha-(methylamino)-isobutyric acid appear to occur by the same population of transport-mediating sites. Both K(m) and V(max) of the Na(+)-sensitive uptake of these three amino acids change with changes in the concentration of Na(+), an effect which is shown to have a theoretical basis. A similarity in the values of Vmax for ten amino acids entering principally by the Na(+)-sensitive agency indicates that differences in their K(m) values probably measure differences in their affinities for that transport-mediating system.
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De Laey P. Die Membranverdauung der Stärke. 3. Mitt. Der Einfluß von alimentären Komponenten des Chymus auf die Membranverdauung der Stärke. ACTA ACUST UNITED AC 1966. [DOI: 10.1002/food.19660100804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Christensen HN. Relations in the Transport of β-Alanine and the α-Amino Acids in the Ehrlich Cell. J Biol Chem 1964. [DOI: 10.1016/s0021-9258(18)97762-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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