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 |
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.
Naming
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.
Function
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 partners
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]
- 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
See also
References
- ↑ 1.0 1.1 1.2 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.
- ↑ 2.0 2.1 2.2 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)
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