PHKG2 explained

Phosphorylase b kinase gamma catalytic chain, testis/liver isoform is an enzyme that in humans is encoded by the PHKG2 gene.^{[1] [2] [3]}

The PHKG2 gene provides instructions for making one piece, the gamma subunit, of the phosphorylase b kinase enzyme. This enzyme is made up of 16 subunits, four each of the alpha, beta, gamma, and delta subunits. (Each subunit is produced from a different gene.) The gamma subunit performs the function of phosphorylase b kinase enzyme, and the other subunits help regulate its activity. This enzyme is found in various tissues, although it is most abundant in the liver and muscles. One version of the enzyme is found in liver cells and another in muscle cells. The gamma-2 subunit produced from the PHKG2 gene is part of the enzyme found in the liver.^[4]

Phosphorylase b kinase plays an important role in providing energy for cells. The main source of cellular energy is a simple sugar called glucose. Glucose is stored in muscle and liver cells in a form called glycogen. Glycogen can be broken down rapidly when glucose is needed, for instance to maintain normal levels of glucose in the blood between meals. Phosphorylase b kinase turns on (activates) another enzyme called glycogen phosphorylase b by converting it to the more active form, glycogen phosphorylase a. When active, this enzyme breaks down glycogen.^[4]

Further reading

• Hanks SK . Homology probing: identification of cDNA clones encoding members of the protein-serine kinase family. . Proc. Natl. Acad. Sci. U.S.A. . 84 . 2 . 388–92 . 1987 . 2948189 . 10.1073/pnas.84.2.388 . 304212 . free . 1987PNAS...84..388H .
• Søvik O, deBarsy T, Maehle B . Phosphorylase kinase deficiency: severe glycogen storage disease with evidence of autosomal recessive mode of inheritance. . Eur. J. Pediatr. . 139 . 3 . 210 . 1983 . 6962066 . 10.1007/BF01377363 . 21587211 .
• Huang CY, Yuan CJ, Livanova NB, Graves DJ . Expression, purification, characterization, and deletion mutations of phosphorylase kinase gamma subunit: identification of an inhibitory domain in the gamma subunit. . Mol. Cell. Biochem. . 127-128 . 7–18 . 1994 . 7935363 . 10.1007/BF01076753 . 22905953 .
• Maichele AJ, Burwinkel B, Maire I, etal . Mutations in the testis/liver isoform of the phosphorylase kinase gamma subunit (PHKG2) cause autosomal liver glycogenosis in the gsd rat and in humans. . Nat. Genet. . 14 . 3 . 337–40 . 1996 . 8896567 . 10.1038/ng1196-337 . 2663835 .
• Lowe ED, Noble ME, Skamnaki VT, etal . The crystal structure of a phosphorylase kinase peptide substrate complex: kinase substrate recognition. . EMBO J. . 16 . 22 . 6646–58 . 1998 . 9362479 . 10.1093/emboj/16.22.6646 . 1170269 .
• Burwinkel B, Shiomi S, Al Zaben A, Kilimann MW . Liver glycogenosis due to phosphorylase kinase deficiency: PHKG2 gene structure and mutations associated with cirrhosis. . Hum. Mol. Genet. . 7 . 1 . 149–54 . 1998 . 9384616 . 10.1093/hmg/7.1.149 . free .
• Burwinkel B, Tanner MS, Kilimann MW . Phosphorylase kinase deficient liver glycogenosis: progression to cirrhosis in infancy associated with PHKG2 mutations (H144Y and L225R) . J. Med. Genet. . 37 . 5 . 376–7 . 2000 . 10905889 . 10.1136/jmg.37.5.376 . 1734590 .
• 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 . 10.1073/pnas.242603899 . 139241 . 2002PNAS...9916899M . free .
• Burwinkel B, Rootwelt T, Kvittingen EA, etal . Severe phenotype of phosphorylase kinase-deficient liver glycogenosis with mutations in the PHKG2 gene. . Pediatr. Res. . 54 . 6 . 834–9 . 2004 . 12930917 . 10.1203/01.PDR.0000088069.09275.10 . free .
• Ota T, Suzuki Y, Nishikawa T, etal . Complete sequencing and characterization of 21,243 full-length human cDNAs. . Nat. Genet. . 36 . 1 . 40–5 . 2004 . 14702039 . 10.1038/ng1285 . free .
• 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 . 10.1101/gr.2596504 . 528928 .
• Beauchamp NJ, Dalton A, Ramaswami U, etal . Glycogen storage disease type IX: High variability in clinical phenotype. . Mol. Genet. Metab. . 92 . 1–2 . 88–99 . 2007 . 17689125 . 10.1016/j.ymgme.2007.06.007 .

External links

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

Notes and References

1. Hanks SK . Messenger ribonucleic acid encoding an apparent isoform of phosphorylase kinase catalytic subunit is abundant in the adult testis . Mol Endocrinol . 3 . 1 . 110–6 . Mar 1989 . 2915644 . 10.1210/mend-3-1-110 . free .
2. Whitmore SA, Apostolou S, Lane S, Nancarrow JK, Phillips HA, Richards RI, Sutherland GR, Callen DF . Grant Robert Sutherland . Isolation and characterization of transcribed sequences from a chromosome 16 hn-cDNA library and the physical mapping of genes and transcribed sequences using a high-resolution somatic cell panel of human chromosome 16 . Genomics . 20 . 2 . 169–75 . Aug 1994 . 8020963 . 10.1006/geno.1994.1150 .
3. Web site: Entrez Gene: PHKG2 phosphorylase kinase, gamma 2 (testis).
4. Web site: PHKG2 gene . ghr.nlm.nih.gov . Genetics home reference . 9 October 2018.