Gi alpha subunit
| G protein subunit alpha i1 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | GNAI1 | ||||||
| NCBI gene | 2770 | ||||||
| HGNC | 4384 | ||||||
| OMIM | 139310 | ||||||
| PDB | 3UMR | ||||||
| RefSeq | NM_002069 | ||||||
| UniProt | P63096 | ||||||
| Other data | |||||||
| Locus | Chr. 7 q21-q22 | ||||||
| |||||||
| G protein subunit alpha i2 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | GNAI2 | ||||||
| NCBI gene | 2771 | ||||||
| HGNC | 4385 | ||||||
| OMIM | 139360 | ||||||
| RefSeq | NM_002070 | ||||||
| UniProt | P04899 | ||||||
| Other data | |||||||
| Locus | Chr. 3 p21 | ||||||
| |||||||
| G protein subunit alpha i3 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | GNAI3 | ||||||
| NCBI gene | 2773 | ||||||
| HGNC | 4387 | ||||||
| OMIM | 139370 | ||||||
| PDB | 2ODE | ||||||
| RefSeq | NM_006496 | ||||||
| UniProt | P08754 | ||||||
| Other data | |||||||
| Locus | Chr. 1 p13 | ||||||
| |||||||
| G protein subunit alpha o1 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | GNAO1 | ||||||
| NCBI gene | 2775 | ||||||
| HGNC | 4389 | ||||||
| OMIM | 139311 | ||||||
| RefSeq | NM_020988 | ||||||
| UniProt | P09471 | ||||||
| Other data | |||||||
| Locus | Chr. 16 q13 | ||||||
| |||||||
Gi alpha subunit (Gαi, or Gi/G0 or Gi protein) is a heterotrimeric G protein subunit that inhibits the production of cAMP from ATP.[1] A mnemonic for remembering this subunit is to look at first letter (Gαi = Adenylyl Cyclase inhibitor).
Receptors
The following G protein-coupled receptors couple to the Gi subunit:
- Acetylcholine M2 & M4 receptors
- Adenosine A1 & A3 receptors
- Adrenergic α2A, α2B, & α2C receptors
- Apelin receptors
- Calcium-sensing receptor
- Cannabinoid receptors (CB1 and CB2)
- Chemokine CXCR4 receptor
- Dopamine D2, D3, D4
- GABAB receptor
- Glutamate mGlu2, mGlu3, mGlu4, mGlu6, mGlu7, & mGlu8 receptors
- Histamine H3 & H4 receptors
- Melatonin MT1, MT2, & MT3 receptors
- Muscarinic M2 receptors
- Hydroxycarboxylic acid receptors: HCA1, HCA2, & HCA3
- Opioid δ, κ, μ, & nociceptin receptors
- Prostaglandin EP1, EP3, FP, & TP receptors
- Serotonin 5-HT1 & 5-HT5 receptors
- Short chain fatty acid receptors: FFAR2 & FFAR3
- Somatostatin sst1, sst2, sst3, sst4 & sst5 receptors
- Trace amine-associated receptor 8
Function
Gi mainly inhibits the cAMP dependent pathway by inhibiting adenylate cyclase activity, decreasing the production of cAMP from ATP, which, in turn, results in decreased activity of cAMP-dependent protein kinase. Therefore, the ultimate effect of Gi is the opposite of cAMP-dependent protein kinase.
It is also attributed a minor role in activation of the phospholipase C pathway.[2] Growth hormone is required for normal postnatal growth, bone growth, regulatory effects on protein, carbohydrate, and lipid metabolism.[3] Although this is mainly a function of the Gq alpha subunit.
Types
There are several types of Gi: Gia1, Gia2, Gia3 and Gia4
Gia1
Gia1 or Gi1 is encoded by the gene GNAI1.
Gia2
Gia2 or Gi2 is encoded by the gene GNAI2.
Gia3
Gia3 or Gi3 is encoded by the gene GNAI3.
See also
References
- ^ Birnbaumer L (April 2007). "Expansion of signal transduction by G proteins. The second 15 years or so: from 3 to 16 alpha subunits plus betagamma dimers". Biochim. Biophys. Acta. 1768 (4): 772–93. doi:10.1016/j.bbamem.2006.12.002. PMC 1993906. PMID 17258171.
- ^ Obál F, Krueger J (2001). "The somatotropic axis and sleep". Rev Neurol (Paris). 157 (11 Pt 2): S12–5. PMID 11924022.
- ^ GeneGlobe -> GHRH Signaling[permanent dead link] Retrieved on May 31, 2009
External links
- Gi+alpha+Subunit at the U.S. National Library of Medicine Medical Subject Headings (MeSH)