MITOCHONDRIAL CYTOCHROME-C-OXIDASE SUBUNIT-IV IS PHOSPHORYLATED BY ANENDOGENOUS KINASE

This study was undertaken to identify novel mitochondrial membrane pro teins that are potential targets for phosphorylation, Mitochondrial me mbranes mere incubated in the. presence of [gamma-P-32]ATP and the Tri ton X-114 extractable protein was subjected to ion-exchange and polyac rylamide gel chromatography to purify major phosphorylated protein of approximately 17000 Da. The determined peptide sequence of the purifie d phosphoprotein corresponded to a segment of cytochrome c oxidase sub unit IV, an inner membrane protein of 17160 Da, The identity of the ph osphoprotein was confirmed by two-dimensional electrophoresis and West ern blotting, The results identify mitochondrial cytochrome c oxidase subunit IV as a protein which is phosphorylated by an endogenous kinas e. (C) 1997 Federation of European Biochemical Societies.