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Gq protein (Gαq, or Gq/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.

guanine nucleotide binding protein (G protein), q polypeptide
Identifiers
SymbolGNAQ
Entrez2776
HUGO4390
OMIM600998
RefSeqNM_002072
UniProtP50148
Other data
LocusChr. 9 q21
guanine nucleotide binding protein (G protein), alpha 11 (Gq class)
Identifiers
SymbolGNA11
Entrez2767
HUGO4379
OMIM139313
RefSeqNM_002067
UniProtP29992
Other data
LocusChr. 19 p13.3
guanine nucleotide binding protein (G protein), alpha 14
Identifiers
SymbolGNA14
Entrez9630
HUGO4382
OMIM604397
RefSeqNM_004297
UniProtO95837
Other data
LocusChr. 9 q21
guanine nucleotide binding protein (G protein), alpha 15 (Gq class)
Identifiers
SymbolGNA15
Entrez2769
HUGO4383
OMIM139314
RefSeqNM_002068
UniProtP30679
Other data
LocusChr. 19 p13.3

Contents

NamingEdit

There has been much debate about the naming of the Gαq. In the initial identification of the protein, it was named G alpha 42, because it runs at 42 kDa on SDS-PAGE. Although, already identified by Micheal Strathmann and Mel Simon, shared the sequence thus naming it G alpha q. However, the "q" in the name is arbitrarily named and does not stand for anything in particular. This nomenclature came from Micheal Strathmann and Mel Simon after their discovery of the protein class in 1989. Essentially, the q designation comes from the fact that Michael Strathmann couldn't use the front end of the alphabet "because those early letters were already reserved for some classes of subunits, the Gz designation had been taken, and Gx seemed too obvious -- and so Gq." Rumors suggest that Gq was named referencing the style magazine GQ.

FunctionEdit

Gq proteins are class of G proteins which work to activate phospholipase C (PLC), participating in a variety of cellular signaling pathways.[1]

The Gq 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, particularly 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 partnersEdit

From modulatory neurotransmitter receptors (amine receptors belonging to rhodopsin family), Gq has been shown to be pre-coupled with Gq-coupled receptors physically and is functionally coupled to e.g. the G-protein coupled receptors:[2]

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]

GenesEdit

See alsoEdit

ReferencesEdit

  1. ^ 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.
  2. ^ a b c 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 linksEdit