Phospholipase C
Phospholipase C 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 plays an important role in eukaryotic cell physiology, particularly signal transduction pathways.
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Human variant
The human variant has EC 3.1.4.11.
Activation
Receptors that activate this pathway are mainly G-protein coupled receptors coupled to the Gq alpha subunit, including:
- Further information: Gq alpha subunit#Examples of GPCR partners
PLC may also be activated by MAP kinase. Activators of this pathway include PDGF and FGF.[1]
Effects
PLC cleaves a phospholipid. In the process, phosphatidylinositol 4,5-bisphosphate (PIP2) is cleaved into diacyl glycerol (DAG) and inositol 1,4,5-triphosphate (IP3). DAG remains on 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, particular calcium channels in the endoplasmic reticulum (ER). These channels are specific to calcium and only allow the passage of calcium to move through. This causes the cytosolic concentration of Calcium to increase, causing a cascade of intracellular changes and activity.[2]
- Further reading:Calcium function in vertebrates
In addition, calcium and DAG together works to activate PKC, which goes on to phosphorylate other things, leading to altered cellular activity.[2]
- Further reading:function of protein kinase C
End effects include taste, manic depression, tumor promotion, etc.[2]
In other organisms
Other phospholipase C enzymes have been identified in bacteria and in trypanosomes, each with their own EC number.
- Phosphoinositide phospholipase C EC 3.1.4.11 The main form found in eukaryotes, especially mammals.
- Zinc dependent phospholipase C family of bacterial enzymes EC 3.1.4.3 that includes alpha toxins
- Phosphatidylinositol diacylglycerol-lyase EC 4.6.1.13 Another related bacterial enzyme.
- Glycosylphosphatidylinositol diacylglycerol-lyase EC 4.6.1.14 A trypanosomal enzyme.
References
- ^ a b c d e Walter F., PhD. Boron (2003). Medical Physiology: A Cellular And Molecular Approaoch. Elsevier/Saunders, 1300. ISBN 1-4160-2328-3. Page 104
- ^ a b c Alberts B, Lewis J, Raff M, Roberts K, Walter P (2002). Molecular biology of the cell, 4th Edition, New York: Garland Science. ISBN 0-8153-3218-1.
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