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G_q protein or G_q/11 is a heterotrimeric G protein subunit that activates phospholipase C (PLC). PLC in turn hydrolyzes phosphatidylinositol (PIP₂) to diacyl glycerol (DAG) and inositol triphosphate (IP₃) signal transduction pathway. DAG acts as a second messenger that activates Protein Kinase C (PKC) and IP₃ helps in phosphorylation of some proteins.

Function

G_q proteins are class of G proteins which work to activate phospholipase C (PLC), participating in a varity of cellular signaling pathways, including taste, manic depression, tumor promotion, etc.^[1]

The G_q protein works by activating PLC. PLC then 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.^[1]

Further reading:Calcium function in humans

In addition, calcium and DAG together works to activate PKC, which goes on to phosphorylate other things, leading to altered cellular activity.^[1]

Further reading:function of protein kinase C

Examples of GPCR partners

From modulatory neurotransmitter receptors (amine receptors belonging to rhodopsin family), G_q is usually coupled to e.g. the G-protein coupled receptors:

• Alpha 1 adrenergic receptors
• 5-HT receptor type 2
• Muscarinic receptors 1, 3 and 5
• Histamine receptor type 1
• Calcitonin receptor

Genes

• GNAQ, GNA11, GNA14, GNA15

See also

• Second messenger system

References

1. ^ ^{a b c} Alberts B, Lewis J, Raff M, Roberts K, Walter P (2002). Molecular biology of the cell, 4^th Edition, New York: Garland Science. ISBN 0-8153-3218-1. 

External links

• MeSH Gq+protein

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Wikipedia content modification information:

• This page was last modified on 6 May 2008, at 18:42.

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