Lack of ability of trypsin‐treated mitochondrial F1‐ATPase to bind the oligomycin‐sensitivity conferring protein (OSCP)

Abstract
Soluble beef-heart mitochondrial F1-ATPase modified in its α-subunit by mild trypsin treatment (α′-F1) can no longer bind oligomycin-sensitivity conferring protein (OSCP) but is still capable of binding to F1-depleted submitochondrial particles, giving rise to a maximally oligomycin-sensitive ATPase, provided the particles contain their native complement of OSCP. When OSCP is removed from the particles, α′-F1 can still bind to the particles, but added OSCP induces only a low degree of oligomycin sensitivity. The possible role of OSCP in the functional coupling of the catalytic (F1) and H+-translocating (Fo) moieties of mitochondrial ATPase is discussed. The results suggest a functional similarity between the OSCP component of mitochondrial ATPase and the δ-subunit of E. coli ATPase, which is in accordance with the structural homology recently found to exist between the two polypeptides.