Phospholipase C

Cleavage sites of phospholipases. Phospholipase C enzymes cut just before the phosphate attached to the R3 moiety.

Phospholipase C (PLC) is a class of enzymes that cleave phospholipids just before the phosphate group (see figure). It is most commonly taken to be synonymous with the human forms of this enzyme, which play an important role in eukaryotic cell physiology, in particular signal transduction pathways. Thirteen kinds of mammalian phospholipase C are classified into six isotypes (β, γ, δ, ε, ζ, η) according to structure.

Mammalian variants

Activation

Receptors that activate this pathway are mainly G protein-coupled receptors coupled to the Gαq subunit, including:

Other, minor, activators than Gαq are:

Effects

PLC mediated cleavage of PIP2 to DAG and IP3

PLC cleaves the phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) into diacyl glycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). DAG remains bound to the membrane, and IP3 is released as a soluble structure into the cytosol. IP3 then diffuses through the cytosol to bind to IP3 receptors, particularly calcium channels in the smooth endoplasmic reticulum (ER). This causes the cytosolic concentration of calcium to increase, causing a cascade of intracellular changes and activity.[3] In addition, calcium and DAG together work to activate protein kinase C, which goes on to phosphorylate other molecules, leading to altered cellular activity.[3] End-effects include taste, tumor promotion, etc.[3]

In other organisms

Other phospholipase C enzymes have been identified in bacteria and in trypanosomes, each with its own EC number

See also

References

  1. ↑ 1.0 1.1 Walter F., PhD. Boron (2003). Medical Physiology: A Cellular And Molecular Approaoch. Elsevier/Saunders. p. 1300. ISBN 1-4160-2328-3. Page 104
  2. ↑ GeneGlobe -> GHRH Signaling Retrieved on May 31, 2009
  3. ↑ 3.0 3.1 3.2 Alberts B, Lewis J, Raff M, Roberts K, Walter P (2002). Molecular biology of the cell (4th ed.). New York: Garland Science. ISBN 0-8153-3218-1.