Cleavage sites of
. Phospholipase C
cut just before the phosphate attached to the R
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 [ edit ]
Activation [ edit ]
Receptors that activate this pathway are mainly
G protein-coupled receptors coupled to the G, including: αq subunit
Other, minor, activators than G
Effects [ edit ]
PLC mediated cleavage of PIP2 to DAG and IP3
PLC cleaves the
phospholipid phosphatidylinositol 4,5-bisphosphate (PIP 2) into diacyl glycerol (DAG) and inositol 1,4,5-trisphosphate (IP 3). DAG remains bound to the membrane, and IP 3 is released as a soluble structure into the cytosol. IP 3 then diffuses through the cytosol to bind to IP, particularly 3 receptors 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. In addition, calcium and DAG together work to activate [3 ] protein kinase C, which goes on to phosphorylate other molecules, leading to altered cellular activity. End-effects include taste, tumor promotion, etc. [3 ] [3 ]
Additionally, phospholipase c plays an important role in the inflammation pathway. The binding of agonists such as
thrombin, epinephrine, or collagen, to platelet surface receptors can trigger the activation of phospholipase C to catalyze the release of arachidonic acid from two major membrane phospholipids, phosphatidylinositol and phosphatidylcholine. Arachadonic acid can then go on into the cyclooxygenase pathway (producing prostoglandins (PGE1, PGE2, PGF2), prostacyclins (PGI2), or thromboxanes (TXA2)), and the lipoxygenase pathway (producing leukotrienes (LTB4, LTC4, LTD4, LTE4)).
In other organisms [ edit ]
Other phospholipase C enzymes have been identified in
bacteria and in trypanosomes, each with its own EC number
See also [ edit ]
References [ edit ]
^ a b Walter F., PhD. Boron (2003). Medical Physiology: A Cellular And Molecular Approaoch. Elsevier/Saunders. p. 1300. ISBN 1-4160-2328-3. Page 104
^ GeneGlobe -> GHRH Signaling Retrieved on May 31, 2009
^ a b c 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.