Gi alpha subunit: Difference between revisions

G protein subunit alpha i3
Identifiers
Symbol	GNAI3
Entrez	2773
HUGO	4387
OMIM	139370
PDB	2ODE
RefSeq	NM_006496
UniProt	P08754
Other data
Locus	Chr. 1 p13

G protein subunit alpha i2
Identifiers
Symbol	GNAI2
Entrez	2771
HUGO	4385
OMIM	139360
RefSeq	NM_002070
UniProt	P04899
Other data
Locus	Chr. 3 p21

G protein subunit alpha i1
Identifiers
Symbol	GNAI1
Entrez	2770
HUGO	4384
OMIM	139310
PDB	3UMR
RefSeq	NM_002069
UniProt	P63096
Other data
Locus	Chr. 7 q21-q22

VisualWikitext

Revision as of 16:57, 18 December 2018

G protein subunit alpha o1
Identifiers
Symbol	GNAO1
Entrez	2775
HUGO	4389
OMIM	139311
RefSeq	NM_020988
UniProt	P09471
Other data
Locus	Chr. 16 q13

G_i alpha subunit (G_αi, or G_i/G₀ or G_i 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 (G_αi = Adenylyl Cyclase inhibitor).

Receptors

The following G protein-coupled receptors couple to the G_i subunit:

Acetylcholine M₂ & M₄ receptors
Adenosine A₁ & A₃ receptors
Adrenergic α_2A, α_2B, & α_2C receptors
Apelin receptors
Calcium-sensing receptor
Cannabinoid receptors (CB1 and CB2)
Chemokine CXCR4 receptor
Dopamine D₂, D₃, D₄
GABA_B receptor
Glutamate mGlu₂, mGlu₃, mGlu₄, mGlu₆, mGlu₇, & mGlu₈ receptors
Histamine H₃ & H₄ receptors
Melatonin MT₁, MT₂, & MT₃ 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

G_i 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 G_i 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 G_q alpha subunit.

Types

There are several types of G_i: Gia1, Gia2, Gia3 and Gia4

Gia1

Gia1 or G_i1 is encoded by the gene GNAI1.

Gia2

Gia2 or G_i2 is encoded by the gene GNAI2.

Gia3

Gia3 or G_i3 is encoded by the gene GNAI3.

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 US National Library of Medicine Medical Subject Headings (MeSH)

[pmid17258171-1] 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.

[2] Obál F, Krueger J (2001). "The somatotropic axis and sleep". Rev Neurol (Paris). 157 (11 Pt 2): S12–5. PMID 11924022.

[GeneGlobe-3] GeneGlobe -> GHRH Signaling^{[permanent dead link]} Retrieved on May 31, 2009

[1]

[2]

[3]

@@ Line 94: / Line 94: @@
 * [[Histamine]] [[Histamine H3 receptor|H<sub>3</sub>]] & [[Histamine H4 receptor|H<sub>4</sub>]] receptors
 * [[Melatonin]] [[MTNR1A|MT<sub>1</sub>]], [[MTNR1B|MT<sub>2</sub>]], & [[MTNR1C|MT<sub>3</sub>]] receptors
-* Hydroxycarboxylic acid receptors [[Niacin receptor 1|HCA2]] & [[Niacin receptor 2|HCA3]]
+* [[Hydroxycarboxylic acid receptors]]: [[HCA1]], [[HCA2]], & [[HCA3]]
 * [[Opioid]] [[Delta Opioid receptor|δ]], [[Kappa Opioid receptor|κ]], [[Mu Opioid receptor|μ]], & [[Nociceptin receptor|nociceptin]] receptors
 * [[Prostaglandin]] [[PTGER1|EP<sub>1</sub>]], [[PTGER3|EP<sub>3</sub>]], [[FP receptor|FP]], & [[Thromboxane receptor|TP]] receptors
@@ Line 108: / Line 108: @@
 G<sub>i</sub> mainly inhibits the [[cAMP dependent pathway]] by inhibiting adenylate cyclase activity, decreasing the production of [[Cyclic adenosine monophosphate|cAMP]] from [[Adenosine triphosphate|ATP]], which, in turn, results in decreased activity of [[cAMP-dependent protein kinase]]. Therefore, the ultimate effect of G<sub>i</sub> is the opposite of [[function of cAMP-dependent protein kinase|cAMP-dependent protein kinase]].
-It is also attributed a minor role in activation of the [[phospholipase C pathway]].<ref>{{cite journal |vauthors=Obál F, Krueger J | title = The somatotropic axis and sleep. | journal = Rev Neurol (Paris) | volume = 157 | issue = 11 Pt 2 | pages = S12–5 | year = 2001 | pmid = 11924022}}</ref> Growth hormone is required for normal postnatal growth, bone growth, regulatory effects on protein, carbohydrate, and lipid metabolism.<ref name=GeneGlobe>[https://www1.qiagen.com/GeneGlobe/PathwayView.aspx?pathwayID=199 GeneGlobe -> GHRH Signaling]{{dead link|date=October 2017 |bot=InternetArchiveBot |fix-attempted=yes }} Retrieved on May 31, 2009</ref> although this is mainly a function of the [[Gq alpha subunit|G<sub>q</sub> alpha subunit]].
+It is also attributed a minor role in activation of the [[phospholipase C pathway]].<ref>{{cite journal |vauthors=Obál F, Krueger J | title = The somatotropic axis and sleep. | journal = Rev Neurol (Paris) | volume = 157 | issue = 11 Pt 2 | pages = S12–5 | year = 2001 | pmid = 11924022}}</ref> Growth hormone is required for normal postnatal growth, bone growth, regulatory effects on protein, carbohydrate, and lipid metabolism.<ref name=GeneGlobe>[https://www1.qiagen.com/GeneGlobe/PathwayView.aspx?pathwayID=199 GeneGlobe -> GHRH Signaling]{{dead link|date=October 2017 |bot=InternetArchiveBot |fix-attempted=yes }} Retrieved on May 31, 2009</ref> Although this is mainly a function of the [[Gq alpha subunit|G<sub>q</sub> alpha subunit]].
 == Types ==

v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list)