Glycine uptake by trout (Salmo trutta) red blood cells.

The present study demonstrates the presence of different amino acid carriers in the membrane of trout red cells. Most glycine is taken up through the Na(+)-dependent system ASC, although the nearly specific Gly system is also active. Besides these carriers, glycine is taken up by means of Na(+)-independent transporters, system L being the most important. A system asc of high affinity and low capacity has been found, and band 3 is unable to transport glycine under physiological conditions. These results suggest that although all these carriers are already present in primitive vertebrates, several differences exist in their properties with respect to those found in mammalian cells.