Phosphorylase kinase

Phosphorylase kinase

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.

Genes

* Alpha: PHKA1, PHKA2
* Beta: PHKB
* Gamma: PHKG1, PHKG2

tructure

Phosphorylase kinase contain 4 calcium ion binding site.

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.

ee also

* calmodulin
* glycogenolysis

External links

*
*
* [http://biop.ox.ac.uk/www/lj2001/johnson/johnson_02.html Overview at ox.ac.uk]
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Look at other dictionaries:

  • Phosphorylase-Kinase — Masse/Länge Primärstruktur 10996 = 4*(1223+1092+386+148) Aminosäuren …   Deutsch Wikipedia

  • phosphorylase kinase — phosphorylase kinase. См. киназа фосфорилазы. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • phosphorylase kinase — phos·phor·y·lase ki·nase (fos forґə lās kiґnās) [EC 2.7.11.19] an enzyme of the transferase class that catalyzes the phosphorylation of (inactive) glycogen phosphorylase b to form (active) glycogen phosphorylase a, a step in the… …   Medical dictionary

  • phosphorylase kinase — The enzyme that regulates the activity of phosphorylase and glycogen synthetase by addition of phosphate groups. A large and complex enzyme, itself regulated by phosphorylation. Integrates the hormonal and calcium signals in muscle …   Dictionary of molecular biology

  • glycogen phosphorylase kinase — gly·co·gen phos·phor·y·lase ki·nase (gliґko jən fos forґə lās kiґnās) phosphorylase kinase …   Medical dictionary

  • hepatic phosphorylase kinase — he·pat·ic phos·phor·y·lase ki·nase (hə patґik fos forґə lās kiґnās) the liver isozyme of phosphorylase kinase …   Medical dictionary

  • liver phosphorylase kinase — liv·er phos·phor·y·lase ki·nase (livґər fos forґə lās kiґnās) the liver isozyme of phosphorylase kinase …   Medical dictionary

  • kinase — [ kinaz ] n. f. • 1902; du gr. kinein « mettre en mouvement » et ase ♦ Biochim. Enzyme capable d activer par phosphorylation un métabolite, un autre enzyme (phosphorylase kinase) ou une protéine impliquée dans la réponse cellulaire à certains… …   Encyclopédie Universelle

  • phosphorylase — (= glycogen phosphorylase) Enzyme that catalyses the sequential removal of glycosyl residues from glycogen to yield one glucose 1 phosphate per reaction. Its activity is controlled by phosphorylation (by phosphorylase kinase) …   Dictionary of molecular biology

  • Phosphorylase — is a family of allosteric enzymes that catalyze the production of glucose 1 phosphate from a polyglucose such as glycogen, starch or maltodextrin.FunctionMore generally, phosphorylases are enzymes that catalyze the addition of a phosphate group… …   Wikipedia

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