FunctionPhosphorylase b kinase catalyzes the phosphorylation of serine in certain substrates, including troponin I. The alpha chain may bind calmodulin.
Tissue specificityMuscle specific. Isoform 1 is predominant in vastus lateralis muscle. Isoform 2 predominates slightly in heart, and it predominates clearly in the other tissues tested.
PathwayGlycan biosynthesis; glycogen metabolism.
Involvement in diseaseGlycogen storage disease 9D (GSD9D) [MIM:300559]: A metabolic disorder characterized by slowly progressive, predominantly distal muscle weakness and atrophy. Clinical features include exercise intolerance with early fatigability, pain, cramps and occasionally myoglobinuria. Note=The disease is caused by mutations affecting the gene represented in this entry.
Sequence similaritiesBelongs to the phosphorylase b kinase regulatory chain family.
Post-translational modificationsAlthough the final Cys may be farnesylated, the terminal tripeptide is probably not removed, and the C-terminus is not methylated.