Proline and glycine uptake by renal brushborder membrane vesicles.

Abstract

Uptake of L-proline and glycine by rat renal brushborder membrane vesicles was osmotically sensitive, pH dependent, and occurred in the absence of proline and glycine metabolism. The uptake system for proline was Na+ gradient dependent, and exhibited a dual system for entry, Km1 = 0.067 mM and Km2 = 5.26 mM. The uptake of glycine was also Na+ gradient dependent, and exhibited a 2 Km system, Km1 = 0.22 mM and Km2 = 4.00 mM. Studies of proline and glycine interactions indicate a shared site which had a lower affinity and higher capacity for glycine than for proline. The high affinity glycine site and low affinity proline site were not shared.