Amino acid transport and intracellular Na + and K + content of chicken erythrocytes genetically selected for high and low leucine transport activity

Abstract

1. 1. Amino acid transport and intracellular Na + and K + content have been studied in two lines of chickens, one high and the other low uptake, selected for their ability to transport leucine into erythrocytes. 2. 2. Low line birds were less effective in absorbing glycine into erythrocytes than were high line birds, the difference in transport being due to a difference in maximal flux ( V max), but not in apparent affinity for transport sites ( k t ). 3. 3. In contrast to glycine uptake, the greater ability of the high line to absorb lysine was found to be due to a difference in both V max and K t . 4. 4. High line erythrocytes were also observed to contain slightly more K + (about 5%) and about 20% less Na + than low line erythrocytes. 5. 5. These results are discussed in terms of the ion dependency of amino acid transport.