Phosphorylase b kinase regulatory subunit alpha, skeletal muscle isoform is an enzyme that in humans is encoded by the PHKA1gene.[5] It is the muscleisoform of Phosphorylase kinase (PhK).
The PHKA1 gene encodes the alpha subunit of muscle phosphorylase kinase (EC 2.7.1.38), a key regulatory enzyme of glycogen metabolism. Phosphorylase kinase consists of 4 copies of an alpha-beta-gamma-delta tetramer. The alpha, beta (PHKB; MIM 172490), and gamma (PHKG1; MIM 172470 and PHKG2; MIM 172471) subunits have several isoforms; the delta subunit is calmodulin (CALM1; MIM 114180). PHKA2 (MIM 306000) encodes the alpha subunit of liver-specific phosphorylase kinase and is also located on the X chromosome.[supplied by OMIM][5]
Wehner M, Clemens PR, Engel AG, Kilimann MW (1995). "Human muscle glycogenosis due to phosphorylase kinase deficiency associated with a nonsense mutation in the muscle isoform of the alpha subunit". Hum. Mol. Genet. 3 (11): 1983–7. doi:10.1093/hmg/3.11.1983. PMID7874115.