IDENTIFICATION OF THE YEAST ARG-11 GENE AS A MITOCHONDRIAL ORNITHINE CARRIER INVOLVED IN ARGININE-BIOSYNTHESIS

The ARG-11 gene in Saccharomyces cerevisiae encodes a protein with the characteristic features of a family of 35 related membrane proteins t hat are encoded in the fungal genome, Some of them are known to transp ort various substrates and products across the inner membranes of mito chondria, but the functions of 29 members of the family are unknown. T he yeast ARG-11 protein has been over-produced as inclusion bodies in Escherichia coli. It has been solubilized in the presence of sarkosgl, re-constituted into liposomes and shown to transport ornithine in exc hange for protons. Its main physiological role is probably to take orn ithine synthesized from glutamate in the mitochondrial matrix to the c ytosol where it is converted to arginine. (C) 1997 Federation of Europ ean Biochemical Societies.