The cytochrome bc(1) and cytochrome c oxidase complexes associate to form a single supracomplex in yeast mitochondria

The mitochondrial electron transport chain complexes are large multisubunit complexes embedded in the inner membrane. We report here that in the yeast Saccharomyces cerevisiae, the cytochrome be, and cytochrome c oxidase comp lexes co-exist as a larger complex of similar to 1000 kDa in the mitochondr ial membrane. Following solubilization with a mild detergent, the cytochrom e bc(1)-cytochrome c oxidase complex remains stable. It was analyzed using the techniques of gel filtration and blue native-polyacrylamide gel electro phoresis. Direct physical. association of subunits of the cytochrome be, co mplex with those of the cytochrome c oxidase complex was verified by co-imm unoprecipitation analysis. Our data indicate that the cytochrome be, comple x is exclusively in association with the cytochrome c oxidase complex in ye ast mitochondria. We term this complex the cytochrome bc(1)-cytochrome c ox idase supracomplex.