The sites of labeling of the beta-subunit of bovine mitochondrial F1-ATPase with 8-azido-ATP

Abstract

Reaction of the photoaffinity label 8-azido-[2-3H] ATP with bovine heart mitochondrial F1-ATPase abolishes its enzyme activity; inhibition is prevented by ATP (Wagenvoord, R.J., van der Kraan, I., and Kemp, A. (1977) Biochim. Biophys. Acta 460, 17-24). More than 65% of the radioactivity is associated with the beta-subunit and about 25% with the alpha-chains. Radioactivity in the beta-subunit is localized in two specific regions. One corresponds to residues 1-12 (Runswick, M.J., and Walker, J.E. (1983) J. Biol. Chem. 258, 3081-3089), a region which is nonessential for catalysis. Radioactivity in the second region is localized predominantly on three amino acids, lysine 301, isoleucine 304, and tyrosine 311. It seems likely that these residues are found in the vicinity of the ATP binding site of F1-ATPase.