Phosphorylase kinase, alpha 1 explained

Phosphorylase b kinase regulatory subunit alpha, skeletal muscle isoform is an enzyme that in humans is encoded by the PHKA1 gene.^[1] It is the muscle isoform 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]^[1]

A deficiency of this enzyme causes glycogen storage disease type IXd (GSD 9D).

Further reading

• Brushia RJ, Walsh DA . Phosphorylase kinase: the complexity of its regulation is reflected in the complexity of its structure. . Front. Biosci. . 4 . 1–3. D618–41 . 1999 . 10487978 . 10.2741/Brushia. free .
• Daube H, Billich A, Mann K, Schramm HJ . Cleavage of phosphorylase kinase and calcium-free calmodulin by HIV-1 protease. . Biochem. Biophys. Res. Commun. . 178 . 3 . 892–8 . 1991 . 1872871 . 10.1016/0006-291X(91)90975-D.
• Meyer HE, Meyer GF, Dirks H, Heilmeyer LM . Localization of phosphoserine residues in the alpha subunit of rabbit skeletal muscle phosphorylase kinase. . Eur. J. Biochem. . 188 . 2 . 367–76 . 1990 . 2108025 . 10.1111/j.1432-1033.1990.tb15413.x .
• Francke U, Darras BT, Zander NF, Kilimann MW . Assignment of human genes for phosphorylase kinase subunits alpha (PHKA) to Xq12-q13 and beta (PHKB) to 16q12-q13. . Am. J. Hum. Genet. . 45 . 2 . 276–82 . 1989 . 2757032 . 1683359 .
• Wehner M, Clemens PR, Engel AG, Kilimann MW . 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 . 1995 . 7874115 . 10.1093/hmg/3.11.1983.
• Wüllrich A, Hamacher C, Schneider A, Kilimann MW . The multiphosphorylation domain of the phosphorylase kinase alpha M and alpha L subunits is a hotspot of differential mRNA processing and of molecular evolution. . J. Biol. Chem. . 268 . 31 . 23208–14 . 1993 . 10.1016/S0021-9258(19)49449-0 . 8226841 . free .
• Strausberg RL, Feingold EA, Grouse LH, etal . Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. . Proc. Natl. Acad. Sci. U.S.A. . 99 . 26 . 16899–903 . 2003 . 12477932 . 139241 . 10.1073/pnas.242603899 . 2002PNAS...9916899M . free .
• Burwinkel B, Hu B, Schroers A, etal . Muscle glycogenosis with low phosphorylase kinase activity: mutations in PHKA1, PHKG1 or six other candidate genes explain only a minority of cases. . Eur. J. Hum. Genet. . 11 . 7 . 516–26 . 2004 . 12825073 . 10.1038/sj.ejhg.5200996 . free .
• Pallen MJ . Glucoamylase-like domains in the alpha- and beta-subunits of phosphorylase kinase. . Protein Sci. . 12 . 8 . 1804–7 . 2004 . 12876330 . 2323967 . 10.1110/ps.0371103.
• Gerhard DS, Wagner L, Feingold EA, etal . The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). . Genome Res. . 14 . 10B . 2121–7 . 2004 . 15489334 . 528928 . 10.1101/gr.2596504 .

External links

• GeneReviews/NCBI/NIH/UW entry on Phosphorylase Kinase Deficiency, Glycogen Storage Disease Type IX

Notes and References

1. Web site: Entrez Gene: PHKA1 phosphorylase kinase, alpha 1 (muscle).