glycogen phosphorylase (PYGL) dimer b + 2 ATP => glycogen phosphorylase (PYGL) dimer a + 2 ADP

Stable Identifier
Reaction [transition]
Homo sapiens
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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.

Literature References
PubMed ID Title Journal Year
13115432 Enzymic conversion of phosphorylase a to phosphorylase b

Cori, GT, Keller, PJ

Biochim Biophys Acta 1953
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

Maichele, AJ, Kilimann, MW, Maire, I, Sovik, O, Burwinkel, B

Nat Genet 1996
10487978 Phosphorylase kinase: the complexity of its regulation is reflected in the complexity of its structure

Walsh, DA, Brushia, RJ

Front Biosci 1999
5461220 Correlation between subunit interactions and enzymatic activity of phosphorylase a. Method for determining equilibrium constants from initial rate measurements

Huang, CY, Graves, DJ

Biochemistry 1970
12930917 Severe phenotype of phosphorylase kinase-deficient liver glycogenosis with mutations in the PHKG2 gene

Chakraborty, PK, Kilimann, MW, Kvittingen, EA, Rootwelt, T, Burwinkel, B

Pediatr Res 2003
12825073 Muscle glycogenosis with low phosphorylase kinase activity: mutations in PHKA1, PHKG1 or six other candidate genes explain only a minority of cases

Vorgerd, M, Kilimann, MW, Moses, SW, Schroers, A, Clemens, PR, Shin, YS, Burwinkel, B, Pongratz, D, Hu, B

Eur J Hum Genet 2003
7847371 X-linked liver phosphorylase kinase deficiency is associated with mutations in the human liver phosphorylase kinase alpha subunit.

Berger, R, Smeitink, JA, Lamers, WH, van Amstel, HK, Malingré, HE, van den Berg, IE, van Beurden, EA, Poll-The, BT

Am J Hum Genet 1995
Catalyst Activity

phosphorylase kinase activity of phosphorylase kinase complex (PHKL) [cytosol]

This event is regulated
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Orthologous Events
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