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

Stable Identifier
R-HSA-71541
Type
Reaction [transition]
Species
Homo sapiens
Compartment
Locations in the PathwayBrowser
General
SVG |   | PPTX  | SBGN
Click the image above or here to open this reaction in the Pathway Browser
The layout of this reaction may differ from that in the pathway view due to the constraints in pathway layout

The cytosolic phosphorylase kinase complex catalyzes the phosphorylation of the subunits of the glycogen phosphorylase (PYGM) dimer. Two forms of phosphorylase kinase complex have been described (Brushia and Walsh 1999). The one annotated here, consisting of four copies each of PHKA1 (alpha regulatory) (Burwinkel et al 2003), PHKB (beta regulatory) (Burwinkel et al. 2003), PHKG1 (gamma catalytic) (Burwinkel et al. 2003) and CALM (calmodulin) subunits is abundant in muscle and its action on the form of phosphorylase (PYGM) abundant in muscle is described.

While initial studies of 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 the human enzyme is inferred here.

Literature References
PubMed ID Title Journal Year
10487978 Phosphorylase kinase: the complexity of its regulation is reflected in the complexity of its structure

Brushia, RJ, Walsh, DA

Front Biosci 1999
13115432 Enzymic conversion of phosphorylase a to phosphorylase b

Keller, PJ, Cori, GT

Biochim Biophys Acta 1953
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
12825073 Muscle glycogenosis with low phosphorylase kinase activity: mutations in PHKA1, PHKG1 or six other candidate genes explain only a minority of cases

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

Eur J Hum Genet 2003
Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
phosphorylase kinase activity of phosphorylase kinase complex (PHKM) [cytosol]
Physical Entity
Activity
This event is regulated
Positively by
Orthologous Events