The reference OMIM entry for this protein is 172471

Phosphorylase kinase, testis/liver, gamma-2; phkg2

DESCRIPTION

The PHKG2 gene encodes the hepatic and testis isoform of the gamma subunit of phosphorylase kinase (PHK; EC 2.7.11.19). The skeletal muscle isoform of the gamma subunit is encoded by the PHKG1 gene (172470).

CLONING

Whitmore et al. (1994) isolated a clone identified as the PHKG2 gene from a heteronuclear cDNA library constructed from a mouse/human somatic cell hybrid that contained chromosome 16. Most of the sequence showed 100% homology with the sequence of an isoform of a catalytic subunit of phosphorylase kinase (Hanks, 1989).

GENE STRUCTURE

Burwinkel et al. (1998) determined that the PHKG2 gene contains 10 exons and spans 9.5 kb. The positions of introns were highly conserved between PHKG2 and PHKG1. The beginning of intron 2 harbors a highly polymorphic GGT/GT microsatellite repeat.

MAPPING

Whitmore et al. (1994) mapped the PHKG2 gene to chromosome 16p12.1-p11.2 by use of a high-resolution somatic cell panel.

MOLECULAR GENETICS

Maichele et al. (1996) reported that autosomal liver-specific PHK deficiency (glycogen storage disease IXc; GSD9C; 613027) was caused by mutations in the PHKG2 gene. They found homozygous PHKG2 mutations in 3 patients of consanguineous parentage. One mutation was a single basepair insertion in codon 89 that caused a frameshift and premature chain termination (172471.0001). The 3 other mutations resulted in nonconservative replacements of amino acid residues that are highly conserved within the catalytic core regions of all protein kinases. The findings suggested that the PHKG2 gene product is the predominant isoform of catalytic gamma subunit of PHK not only in testis but also in liver, erythrocytes, and possibly other nonmuscle tissues. Burwinkel et al. (1998) identified homozygous translation-terminating mutations in the PHKG2 gene, R442X (17241.0004) and 277delC (172471.0005), in 2 patients with liver phosphorylase kinase deficiency who developed cirrhosis in childhood. As liver phosphorylase kinase deficiency is generally a benign condition and progression to cirrhosis is very rare, the findings suggested to the authors that PHKG2 mutations are particularly associated with an increased cirrhosis risk. Burwinkel et al. (2000) reported compound heterozygosity for missense mutations in the PHKG2 gene (172471.0006; 172471.0007) in a child with phosphorylase kinase deficiency and cirrhosis. Roscher et al. (2014) reported 3 novel mutations in the PHKG2 gene resulting in GSD IXc.

ANIMAL MODEL

Malthus et al. (1980) described deficiency of liver phosphorylase kinase in rats and concluded that it was an autosomal recessive trait. Apart from hepatomegaly, the affected rats appear healthy. Clark and Haynes (1988) described autosomal recessive glycogen storage disease in the rat (gsd/gsd). Maichele et al. (1996) identified a homozygous mutation in the rat Phkg2 gene (D215N) as responsible for the gsd phenotype in the rat. ... More on the omim web site

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Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated

Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated

Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated

June 20, 2017: Protein entry updated
Automatic update: comparative model was added.

March 16, 2016: Protein entry updated
Automatic update: OMIM entry 172471 was added.

Jan. 25, 2016: Protein entry updated
Automatic update: model status changed