The mitochondrial ATP synthase inhibitor protein binds near the C‐terminus of the F₁ β‐subunit

The specific, mitochondrial ATP synthase protein (IF1) was covalently cross-linked to its binding site on the catalytic sector of the enzyme (F1-ATPase). The cross-linked complex was selectively cleaved, leaving IF1 intact to facilitate the subsequent purification of the F1 fragment to which IF1 was cross-linked. This fragment was identified by sequence analysis as comprising residues 394-459 on the F1 beta-subunit, near the C-terminus. This finding is discussed in the light of secondary structure predictions for both IF1 and the F1 beta-subunit, and sequence homologies between mitochondrial and other ATP synthases.