The alpha-subunit of the maize F(1)-ATPase is synthesised in the mitochondrion

Abstract

The F(1)-ATPase complex has been purified from maize (Zea mays L.) mitochondria and shown to consist of five subunits with mol. wts. of 58 000 (alpha), 56 000 (beta), 35 000 (gamma), 22 000 (delta) and 8000 (epsilon). The alpha-subunit co-migrates on one- and two- dimensional isoelectric focussing-SDS polyacrylamide gels with the major polypeptide synthesised by isolated mitochondria. One-dimensional proteolytic peptide mapping and immunoprecipitation confirms that the alpha-subunit is a mitochondrial translation product and therefore presumably encoded in mitochondrial DNA. This contrasts with the situation in animal and fungal cells where all five subunits of the F(1)-ATPase are encoded by the nuclear genome and synthesised on cytosolic ribosomes.