YidC/Oxa1p/Alb3: evolutionarily conserved mediators of membrane protein assembly

This review focuses on a novel, evolutionarily conserved mediator of membra ne protein assembly in bacteria, mitochondria and chloroplasts, This factor is designated YidC in Escherichia coli, and is localized in the inner memb rane. YidC is homologous to Oxa1p in the mitochondrial inner membrane and A lb3 in the chloroplast thylakoid membrane, but does mot seem to have a homo logue in the endoplasmic reticulum membrane, It has been suggested that Yid C operates both as a separate unit and in connection with the SecYEG-transl oclon depending on the substrate membrane protein that is integrated into t he membrane. Mitochondria do not possess a SecYEG-like complex and Oxa1p is thought to form, or to contribute to the formation of, at novel translocon in the mitochondrial inner membrane. Alb3 in the chloroplast thylakoid mem brane is, just like YidC and Oxa1p, involved in membrane protein assembly, but only few details are known. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.