Phosphorylation and kinetics of mammalian cytochrome c oxidase.

ABSTRACT: The influence of protein phosphorylation on the kinetics of cytochrome c oxidase was investigated by applying Western blotting, mass spectrometry, and kinetic measurements with an oxygen electrode. The isolated enzyme from bovine heart exhibited serine, threonine, and/or tyrosine phosphorylation in various subunits, except subunit I, by using phosphoamino acid-specific antibodies. The kinetics revealed slight inhibition of oxygen uptake in the presence of ATP, as compared with the presence of ADP. Mass spectrometry identified the phosphorylation of Ser-34 at subunit IV and Ser-4 and Thr-35 at subunit Va. Incubation of the isolated enzyme with protein kinase A, cAMP, and ATP resulted in serine and threonine phosphorylation of subunit I, which was correlated with sigmoidal inhibition kinetic

SUBMITTER: Helling S 

PROVIDER: S-EPMC2556016 | biostudies-literature | 2008 Sep

REPOSITORIES: biostudies-literature