The mitochondrial ATP synthase inhibitor protein binds near the C-terminus of the F 1 β-subunit

Abstract

The specific, mitochondrial ATP synthase protein (IF 1) was covalently cross-linked to its binding site on the catalytic sector of the enzyme (F 1-ATPase). The cross-linked complex was selectively cleaved, leaving IF 1 intact to facilitate the subsequent purification of the F 1 fragment to which IF 1 was cross-linked. This fragment was identified by sequence analysis as comprising residues 394–459 on the F 1 β-subunit, near the C-terminus. This finding is discussed in the light of secondary structure predictions for both IF 1 and the F 1 β-subunit, and sequence homologies between mitochondrial and other ATP synthases.