Gq alpha subunit

guanine nucleotide binding protein (G protein), q polypeptide
Identifiers
Symbol	GNAQ
Entrez	2776
HUGO	4390
OMIM	600998
RefSeq	NM_002072
UniProt	P50148
Other data
Locus	Chr. 9 q21

guanine nucleotide binding protein (G protein), alpha 11 (Gq class)
Identifiers
Symbol	GNA11
Entrez	2767
HUGO	4379
OMIM	139313
RefSeq	NM_002067
UniProt	P29992
Other data
Locus	Chr. 19 p13.3

guanine nucleotide binding protein (G protein), alpha 14
Identifiers
Symbol	GNA14
Entrez	9630
HUGO	4382
OMIM	604397
RefSeq	NM_004297
UniProt	O95837
Other data
Locus	Chr. 9 q21

guanine nucleotide binding protein (G protein), alpha 15 (Gq class)
Identifiers
Symbol	GNA15
Entrez	2769
HUGO	4383
OMIM	139314
RefSeq	NM_002068
UniProt	P30679
Other data
Locus	Chr. 19 p13.3

G_q protein (G_αq, or G_q/11) is a heterotrimeric G protein subunit that activates phospholipase C (PLC). PLC in turn hydrolyzes Phosphatidylinositol 4,5-bisphosphate (PIP₂) to diacyl glycerol (DAG) and inositol trisphosphate (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 variety of cellular signaling pathways.^[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-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, 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 vertebrates

In addition, calcium and DAG together work to activate PKC, which goes on to phosphorylate other molecules, 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 has been shown to be pre-coupled with G_q-coupled receptors physically and is functionally coupled to e.g. the G-protein coupled receptors:^[2]

• 5-HT₂ serotonergic receptors
• Alpha-1 adrenergic receptor
• Vasopressin type 1 receptors: 1A and 1B
• Angiotensin II receptor type 1
• Calcitonin receptor
• Histamine H1 receptor
• Metabotropic glutamate receptor, Group I
• M₁, M₃, and M₅ muscarinic receptors^[2]
• Trace amine-associated receptor 1

It has been shown that Gq proteins are preassembled (pre-coupled) with Gq-coupled receptors (such as M₃ receptor. The common polybasic domain in the C-tail of Gq-coupled receptors is necessary for the receptor-G protein preassembly.^[2]

Genes

• GNAQ, GNA11, GNA14, GNA15

See also

• Second messenger system

References

1. 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.
2. Kou Qin, Chunmin Dong, Guangyu Wu & Nevin A Lambert (August 2011). "Inactive-state preassembly of Gq-coupled receptors and Gq heterotrimers". Nature Chemical Biology 7 (11): 740–747. doi:10.1038/nchembio.642. PMC 3177959. PMID 21873996.

External links

• Gq protein at the US National Library of Medicine Medical Subject Headings (MeSH)