Amino acid transport in blood cells II. Patterns of transport of some amino acids in mammalian reticulocytes and mature red blood cells

Amino acid transport and its cationic requirements have been studied in mammalian reticulocytes and mature red blood cells. Sodium is required for the concentrative uptake of AIB (alpha-aminoisobutyric acid-1-C¹⁴) glycine and alanine by human and rat reticulocytes, whereas the concentrative uptake of ACPC (aminocyclopentane-carboxylic acid-C¹⁴), histidine, and lysine was readily demonstrable without added sodium. Amino, acid uptake was markedly inhibited by the sulfhydryl reagents p-hydroxymercuribenzoate and N-ethyl-maleimide. Puromycin completely blocked the uptake of alanine and lysine into protein without interfering with the intracellular accumulation of these amino acids. The capacity to concentrate amino acids against a chemical gradient is markedly reduced or absent in the mature red cell. Some possible explanations for this metabolic change are discussed.