Characterization of proteins phosphorylated by the cAMP-dependent protein kinase of bovine heart mitochondria

Characterization of two mitochondrial proteins of M(r) 42 and 18 kDa, respectively, phosphorylated by the cAMP-dependent protein kinase of bovine heart mitochondria (mtPKA), is presented, A 42 kDa protein is found to be loosely associated to complexes I, UI and IV of the respiratory chain and complex V (ATP synthase) in the inner mitochondrial membrane, An 18 kDa protein is associated to complex I in the inner membrane and in a purified preparation of this complex where it can be phosphorylated by the isolated catalytic subunit of PKA.