ATP synthase complex from bovine heart mitochondria: the oligomycin sensitivity conferring protein is essential for dicyclohexyl carbodiimide-sensitive ATPase.

The requirement of bovine heart mitochondrial oligomycin sensitivity conferring protein (OSCP) in conferring dicyclohexylcarbodiimide (DCCD)-sensitivity to membrane-bound F1 was investigated by using OSCP-depleted membrane fraction (UF0) of ATP synthase. The ATPase activity of UF0-F1 was completely insensitive to DCCD while that of UF0-F1-OSCP was inhibited 95% by 16 microM DCCD. Both UF0-F1 and UF0-F1-OSCP complexes bound 5 nmol [14C]DCCD/mg UF0, and all the radioactivity was found to be associated with the DCCD-binding proteolipid. The data suggest that OSCP may be necessary for transmitting not only energy-linked signals, but also signals induced by F0 inhibitory ligands in mitochondrial energy transduction.