Transport of amino acids into the estrogen-primed uterus IV. Effects of sulfhydryl agents on the uptake in vitro

Abstract

1. 1. Sulfhydryl agents have been found to stimulate uptakes of some amino acids by the immature rat uterus in vitro, and to inhibit the uptakes of others. Those whose uptakes were stimulated can enter the cells well by the L transport system for amino acids, while those inhibited use the A system. Uptake of 1-aminocyclopentanecarboxylic acid (cycloleucine), which probably involves both systems, could be stimulated or inhibited, depending on the conditions.2. 2. The results suggest that the uterus contains at least two kinds of groups that react with SH agents and are involved in amino acid transport. N-Ethylmalcimide combines relatively rapidly with one type, apparently involving the L system to produce stimulation of amino acid transport; but it combines more slowly with the other, the A system, to inhibit transport.3. 3. The stimulation of amino acid uptake by estradiol, which probably involves the A system, can be inhibited by N-ethylmaleimide. This inhibition, however, is apparently not due to an action of N-ethylmaleimide to prevent a possible binding of the hormone to necessary uterine sites.4. 4. The stimulation of amino acid uptake by N-ethylmaleimide appears to be independent of the stimulation by estradiol.