Phosphorylase kinase
From Wikipedia, the free encyclopedia
Phosphorylase kinase is a serine/threonine-specific protein kinase which converts glycogen phosphorylase b to glycogen phosphorylase a, activating it to release glucose-1-phosphate from glycogen.
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[edit] Genes
[edit] Structure
Phosphorylase kinase contain 4 calcium ion binding site.
[edit] Regulation
The enzyme is regulated by both allosteric regulation and reversible phosphorylation.
Hormones, nerve impulses and muscle contraction stimulate the release of calcium ions; the allosteric activator, calcium ions bind to the beta subunits of the enzymes and partly activate the enzyme activities.
Hormones also stimulate the phosphorylation of protein kinase A, which catalyse the phosphorylation of sigma subunits on the phosphorylase kinases; the phosphorylation partly activate the activities of the enzymes.
The phosphorylase kinase is completely activated when the beta subunit is calcium-ion-bound and the sigma subunit is phosphorylated at the same time.
[edit] See also
[edit] External links
- EC 2.7.11.19
- MeSH Phosphorylase+kinase
- Overview at ox.ac.uk
- Nadeau O, Gogol E, Carlson G (2005). "Cryoelectron microscopy reveals new features in the three-dimensional structure of phosphorylase kinase.". Protein Sci 14 (4): 914–20. doi:. PMID 15741332.
- Brushia R, Walsh D (1999). "Phosphorylase kinase: the complexity of its regulation is reflected in the complexity of its structure.". Front Biosci 4: D618–41. doi:. PMID 10487978.
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