PHKA1

Phosphorylase kinase is a polymer of 16 subunits, four each of alpha, beta, gamma and delta. The alpha subunit includes the skeletal muscle and hepatic isoforms, and the skeletal muscle isoform is encoded by this gene. The beta subunit is the same in both the muscle and hepatic isoforms, and encoded by one gene. The gamma subunit also includes the skeletal muscle and hepatic isoforms, which are encoded by two different genes. The delta subunit is a calmodulin and can be encoded by three different genes. The gamma subunits contain the active site of the enzyme, whereas the alpha and beta subunits have regulatory functions controlled by phosphorylation. The delta subunit mediates the dependence of the enzyme on calcium concentration. Mutations in this gene cause glycogen storage disease type 9D, also known as X-linked muscle glycogenosis. Alternatively spliced transcript variants encoding different isoforms have been identified in this gene. A pseudogene has been found on chromosome 1.

Full Name

Phosphorylase Kinase Regulatory Subunit Alpha 1

Function

Phosphorylase b kinase catalyzes the phosphorylation of serine in certain substrates, including troponin I. The alpha chain may bind calmodulin.

Biological Process

Generation of precursor metabolites and energyManual Assertion Based On ExperimentTAS:ProtInc
Glycogen metabolic processManual Assertion Based On ExperimentTAS:ProtInc

Cellular Location

Cell membrane

Involvement in disease

Glycogen storage disease 9D (GSD9D):
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.

PTM

Although the final Cys may be farnesylated, the terminal tripeptide is probably not removed, and the C-terminus is not methylated.