Amino acid transport in human and in sheep erythrocytes
- 26 September 1980
- journal article
- research article
- Published by The Royal Society in Proceedings of the Royal Society of London. B. Biological Sciences
- Vol. 209 (1176), 355-375
- https://doi.org/10.1098/rspb.1980.0100
Abstract
Amino acid transport was compared in human and in sheep erythrocytes. Kinetic studies established that human cells have 3 discrete amino acid transport systems, designated L, Ly+ and ASC. The L system is partially stereospecific, with a preference for large neutral amino acids. L-leucine has a 3-fold lower apparent Km and a 2-fold smaller Vmax than D-leucine. Alanine, cysteine and possibly dibasic amino acids are transported by this route, but with a low affinity. The Ly+ system is highly stereoselective, and specific for dibasic amino acids, including arginine. The ASC system is Na-dependent and selective for neutral amino acids of intermediate size. It has a particularly low apparent Km for cysteine and is stereospecific. Sheep erythrocytes lack these systems. Instead they possess an additional system (C system) responsible for the transport both of neutral and of dibasic amino acids, with cysteine as the optimal substrate. Although the substrate specificities of the human ASC and sheep C systems are similar, the sheep system does not require Na and has considerably higher apparent Km values. Dibasic amino acid transport (of lysine, but not of arginine) by the C system does not require Na and has considerably higher apparent Km values. Dibasic amino acid transport (of lysine, but not of arginine) by the C system occurs with a low affinity.This publication has 9 references indexed in Scilit:
- Nucleoside transport in sheep erythrocytes: genetically controlled transport variation and its influence on erythrocyte ATP concentrations.The Journal of Physiology, 1978
- Substrate specificity of amino acid transport in sheep erythrocytesBiochemical Journal, 1977
- The genetic control of red cell glutathione deficiencies in Finnish Landrace and Tasmanian Merino sheep and in crosses between these breedsThe Journal of Agricultural Science, 1976
- CystinosisAmerican Journal Of Medicine, 1968
- Fitting the Rectangular HyperbolaBiometrics, 1966
- Contrasts in Neutral Amino Acid Transport by Rabbit Erythrocytes and ReticulocytesJournal of Biological Chemistry, 1965
- Migration of Amino Acids across the Membrane of the Human ErythrocyteJournal of Biological Chemistry, 1964
- The determination of enzyme inhibitor constantsBiochemical Journal, 1953