The cytosolic phosphorylase kinase complex catalyzes the phosphorylation of glycogen phosphorylase (PYGL). Two forms of phosphorylase kinase complex have been described (Brushia and Walsh 1999). The one annotated here, consisting of four copies each of PHKA2 (alpha regulatory) (van den Berg et al. 1995), PHKB (beta regulatory) (Burwinkel et al. 2003a), PHKG2 (gamma catalytic) (Burwinkel et al. 2003b; Maichele et al. 2006) and CALM (calmodulin) subunits is abundant in liver and its action on the form of phosphorylase (PYGL) abundant in liver is described.
While initial studies of glycogen phosphorylase PGYM from rabbit muscle suggested that it is a homotetramer (Keller and Cori 1953), more recent work indicates that under physiological conditions the enzyme occurs as a homodimer (Huang and Graves 1970) and a dimeric structure for human PYGL enzyme is inferred here.
|phosphorylase kinase complex (PHKL)||phosphorylase kinase activity (0004689)|
|10487978||Phosphorylase kinase: the complexity of its regulation is reflected in the complexity of its structure||Front Biosci||1999|
|12825073||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||2003|
|5461220||Correlation between subunit interactions and enzymatic activity of phosphorylase a. Method for determining equilibrium constants from initial rate measurements||Biochemistry||1970|
|13115432||Enzymic conversion of phosphorylase a to phosphorylase b||Biochim Biophys Acta||1953|
|12930917||Severe phenotype of phosphorylase kinase-deficient liver glycogenosis with mutations in the PHKG2 gene||Pediatr Res||2003|
|7847371||X-linked liver phosphorylase kinase deficiency is associated with mutations in the human liver phosphorylase kinase alpha subunit.||Am J Hum Genet||1995|
|8896567||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||1996|