Glycine transport by hemolysed and restored pigeon red cells Effects of a Donnan-induced electrical potential on entry and exit kinetics

Vidaver, George A.; Shepherd, Sara L.; Lagow, Joyce B.; Wiechelman, Karen J.

doi:10.1016/0005-2787(76)90512-8

Cited by 7 publications

(2 citation statements)

References 37 publications

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“…Glycine transport in these cells is mediated by a specific transport system, designated system Gly, which requires both Na + and C1-for activity. In the pigeon erythrocyte, system Gly operates with a presumed Na+/C1-/amino-acid coupling ratio of 2 : 1 : 1 [32,50]. Hill-type analyses of the relationship between taurine transport activity and Na + and C1-concentration in fish erythrocytes suggest that the system also functions with an apparent Na+/C1-/taurine coupling ratio of 2:1:1.…”

Section: Discussionmentioning

confidence: 94%

Volume-sensitive taurine transport in fish erythrocytes

1987

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Taurine plays an important role in cell volume regulation in both vertebrates and invertebrates. Erythrocytes from two euryhaline fish species, the eel (Anguilla japonica) and the starry flounder (Platichthys stellatus) were found to contain high intracellular concentrations of this amino acid (approximately equal to 30 mmol per liter of cell water). Kinetic studies established that the cells possessed a saturable high-affinity Na+-dependent beta-amino-acid transport system which also required Cl- for activity (apparent Km (taurine) 75 and 80 microM; Vmax 0.85 and 0.29 mumol/g Hb per hr for eel (20 degrees C) and flounder cells (10 degrees C), respectively. This beta-system operated with an apparent Na+/Cl-/taurine coupling ratio of 2:1:1. A reduction in extracellular osmolarity, leading to an increase in cell volume, reversibly decreased the activity of the transporter. In contrast, low medium osmolarity stimulated the activity of a Na+-independent nonsaturable transport route selective for taurine, gamma-amino-n-butyric acid and small neutral amino acids, producing a net efflux of taurine from the cells. Neither component of taurine transport was detected in human erythrocytes. It is suggested that these functionally distinct transport routes participate in the osmotic regulation of intracellular taurine levels and hence contribute to the homeostatic regulation of cell volume. Volume-induced increases in Na+-independent taurine transport activity were suppressed by noradrenaline and 8-bromoadenosine-3', 5'-cyclic monophosphate, but unaffected by the anticalmodulin drug, pimozide.

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Section: Discussionmentioning

confidence: 94%

Volume-sensitive taurine transport in fish erythrocytes

1987

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“…Although the system is rheogenic (Benderoff et al, 1978), it is possible that the chloride dependence reflects either a mechanism involving a singly charged complex of transporter, C, two sodium ions, glycine and chloride (Na2C1.C.Gly) + as depicted by Vidaver et al (1976), or that the chloridedependence reflects only the highly electrogenic character of a complex comprising 1 glycine molecule and 2 Na-% i.e., (Na2.C.Gly) 2+ whereby a highly permeant anion such as chioride rapidly dissipates any (inhibitory) electrical gradient. A consequence of the high chloride conductance, relative to Na + or K + conductance (for sheep red cells, see Tosteson et al, 1972) is that the membrane potential of the vesicles is effectively clamped at a value close to zero.…”

Section: Discussionmentioning

confidence: 99%

Na+-coupled glycine transport in reticulocyte vesicles of distinct sidedness: Stoichiometry and symmetry

Weigensberg

Blostein

1985

J. Membrain Biol.

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Sodium-coupled glycine transport has been studied using membrane vesicles of distinct sidedness, either inside-out or right side-out, prepared from sheep reticulocytes. The activity is chloride dependent and characterized by high and low apparent affinities for glycine (K'm approximately equal to 0.5 mM and greater than 10 mM) for both types of vesicles as well as intact cells. Transport is symmetrical with respect to similar apparent affinity constants for glycine, for both the high- and low-affinity systems, and for sodium. Direct measurements of the sodium/glycine coupling indicate a ratio of 2:1, consistent with kinetic data fitted to a Hill-type equation describing glycine flux as a function of sodium concentration.

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Energetics of Amino Acid Transport

Eddy¹

1992

Mammalian Amino Acid Transport

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Glycine transport by hemolysed and restored pigeon red cells Effects of a Donnan-induced electrical potential on entry and exit kinetics

Cited by 7 publications

References 37 publications

Volume-sensitive taurine transport in fish erythrocytes

Volume-sensitive taurine transport in fish erythrocytes

Na+-coupled glycine transport in reticulocyte vesicles of distinct sidedness: Stoichiometry and symmetry

Energetics of Amino Acid Transport

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