PROLINE TRANSPORT IN RAT-KIDNEY MITOCHONDRIA

Proline transport in rat kidney mitochondria was investigated both by using isotopic techniques and by spectroscopic measurements, in which proline metabolism was essentially allowed to occur. Widely used crite ria for demonstrating the occurrence of carrier-mediated transport wer e successfully applied in both cases. Differences found in the K-m and V-max values, in pH and temperature dependence of proline transport, and in the inhibitor sensitivity demonstrate the existence of two sepa rate translocators for proline in rat kidney mitochondria, i.e., the p roline uniporter and the proline/glutamate antiporter. Efflux of gluta mate via glutamate/OH- translocator following proline uptake by mitoch ondria was experimentally ruled out. Discussion is also made of the po ssible role of such translocators in proline metabolism and in the put ative proline/glutamate shuttle. (C) 1994 Academic Press, Inc.