From Surf Wiki (app.surf) — the open knowledge base

G protein-coupled inwardly rectifying potassium channel

Family of lipid-gated inward-rectifier potassium ion channels

Field	Value
Name	potassium inwardly rectifying channel, subfamily J, member 3
HGNCid	6264
Symbol	KCNJ3
AltSymbols	Kir3.1, GIRK1, KGA
IUPHAR_id	yes
EntrezGene	3760
OMIM	601534
RefSeq	NM_002239
UniProt	P48549
Chromosome	2
Arm	q
Band	24.1

The G protein-coupled inwardly rectifying potassium channels (GIRKs) are a family of lipid-gated inward-rectifier potassium ion channels which are activated (opened) by the signaling lipid PIP2 and a signal transduction cascade starting with ligand-stimulated G protein-coupled receptors (GPCRs). GPCRs in turn release activated G-protein βγ- subunits (Gβγ) from inactive heterotrimeric G protein complexes (Gαβγ). Finally, the Gβγ dimeric protein interacts with GIRK channels to open them so that they become permeable to potassium ions, resulting in hyperpolarization of the cell membrane. G protein-coupled inwardly rectifying potassium channels are a type of G protein-gated ion channels because of this direct interaction of G protein subunits with GIRK channels. The activation likely works by increasing the affinity of the channel for PIP2. In high concentration PIP2 activates the channel absent G-protein, but G-protein does not activate the channel absent PIP2.

GIRK1 to GIRK3 are distributed broadly in the central nervous system, where their distributions overlap. GIRK4, instead, is found primarily in the heart.

Subtypes

protein	gene	aliases
GIRK1		Kir3.1
GIRK2		Kir3.2
GIRK3		Kir3.3
GIRK4		Kir3.4

Examples

A wide variety of G protein-coupled receptors activate GIRKs, including the M2-muscarinic, A1-adenosine, α2-adrenergic, D2-dopamine, μ- δ-, and κ-opioid, 5-HT1A serotonin, somatostatin, galanin, m-Glu, GABAB, TAAR1, CB1 and CB2, and sphingosine-1-phosphate receptors.

Examples of GIRKs include a subset of potassium channels in the heart, which, when activated by parasympathetic signals such as acetylcholine through M2 muscarinic receptors, causes an outward current of potassium, which slows down the heart rate. These are called muscarinic potassium channels (IKACh) and are heterotetramers composed of two GIRK1 and two GIRK4 subunits.

References

Dascal N. (1997). "Signalling via the G protein-activated K⁺ channels". Cell. Signal..
(December 1998). "G protein regulation of potassium ion channels". Pharmacological Reviews.
(March 1995). "Molecular cloning of a mouse G-protein-activated K+ channel (mGIRK1) and distinct distributions of three GIRK (GIRK1, 2 and 3) mRNAs in mouse brain". Biochem. Biophys. Res. Commun..
(June 1996). "IRK(1-3) and GIRK(1-4) inwardly rectifying K+ channel mRNAs are differentially expressed in the adult rat brain". J. Neurosci..
(December 1997). "Developmental expression of the GIRK family of inward rectifying potassium channels: implications for abnormalities in the weaver mutant mouse". Brain Res..
(2011). "Electrophysiological effects of trace amines on mesencephalic dopaminergic neurons". Front Syst Neurosci.
(October 2008). "Cannabinoid Receptors 1 and 2 (CB1 and CB2), Their Distribution, Ligands and Functional Involvement in Nervous System Structures — A Short Review". Pharmacology Biochemistry and Behavior.
(1995). "Identification of domains conferring G protein regulation on inward rectifier potassium channels". Cell.
(1999). "Structure, G protein activation, and functional relevance of the cardiac G protein-gated K⁺ channel, I_KACh". Ann. N. Y. Acad. Sci..
(1995). "The G-protein-gated atrial K⁺ channel I_KACh is a heteromultimer of two inwardly rectifying K⁺-channel proteins". Nature.
(1998). "Number and stoichiometry of subunits in the native atrial G-protein-gated K⁺ channel, I_KACh". J. Biol. Chem..

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

ion-channels

Want to explore this topic further?

Ask Mako anything about G protein-coupled inwardly rectifying potassium channel — get instant answers, deeper analysis, and related topics.

Research with Mako

Free with your Surf account

Content sourced from Wikipedia, available under CC BY-SA 4.0.

This content may have been generated or modified by AI. CloudSurf Software LLC is not responsible for the accuracy, completeness, or reliability of AI-generated content. Always verify important information from primary sources.

Report