An F1-ATPase beta-subunit precursor lacking an internal tetramer-forming domain is imported into mitochondria in the absence of ATP.

Post-translational import of the F1-ATPase beta-subunit precursor into isolated mitochondria requires both an energized inner membrane and nucleoside triphosphate hydrolysis on the organelle surface. Nested internal deletions of the F1 beta-precursor which progressively move a 128-residue carboxyl-terminal domain of the protein closer to the amino terminus reveal an abrupt transition between residues 122 and 144 to a form of the protein which is imported in the absence of added ATP. This transition region of the F1 beta-precursor is the same sequence which we have defined in earlier studies is required for formation of a tetramer following in vitro translation of the F1 beta-precursor. These data indicate that part of the requirement for ATP in the import of mitochondrial precursors may be involved in the reorganization of oligomeric species on the membrane surface which are formed following their translation.