The α-subunit of the maize F1 -ATPase is synthesised in the mitochondrion

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Abstract
The F1‐ATPase complex has been purified from maize (Zea mays L.) mitochondria and shown to consist of five subunits with mol. wts. of 58 000 (α), 56 000 (β), 35 000 (γ), 22 000 (δ) and 8000 (ε). The α‐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 α‐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 F1‐ATPase are encoded by the nuclear genome and synthesised on cytosolic ribosomes.