G protein-coupled inwardly-rectifying potassium channel

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potassium inwardly-rectifying channel, subfamily J, member 3
Identifiers
Symbol KCNJ3
Alt. symbols Kir3.1, GIRK1, KGA
IUPHAR 434
Entrez 3760
HUGO 6264
OMIM 601534
RefSeq NM_002239
UniProt P48549
Other data
Locus Chr. 2 q24.1
potassium inwardly-rectifying channel, subfamily J, member 6
Identifiers
Symbol KCNJ6
Alt. symbols KCNJ7, Kir3.2, GIRK2, KATP2, BIR1, hiGIRK2
IUPHAR 435
Entrez 3763
HUGO 6267
OMIM 600877
RefSeq NM_002240
UniProt P48051
Other data
Locus Chr. 21 q22.1
potassium inwardly-rectifying channel, subfamily J, member 9
Identifiers
Symbol KCNJ9
Alt. symbols Kir3.3, GIRK3
IUPHAR 436
Entrez 3765
HUGO 6270
OMIM 600932
RefSeq NM_004983
UniProt Q92806
Other data
Locus Chr. 1 q23.2
potassium inwardly-rectifying channel, subfamily J, member 5
Identifiers
Symbol KCNJ5
Alt. symbols Kir3.4, CIR, KATP1, GIRK4
IUPHAR 437
Entrez 3762
HUGO 6266
OMIM 600734
RefSeq NM_000890
UniProt P48544
Other data
Locus Chr. 11 q24

The G protein-coupled inwardly-rectifying potassium channels (GIRKs) are a family of inward-rectifier potassium ion channels which are activated (opened) via a signal transduction cascade starting with ligand-stimulated G protein-coupled receptors (GPCRs).[1][2] 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.[3] G protein-coupled inwardly-rectifying potassium channels are a type of G protein-gated ion channels because of this direct activation of GIRK channels by G protein subunits.

GIRK1 to GIRK3 are distributed broadly in the central nervous system, where their distributions overlap.[4][5][6] GIRK4, instead, is found primarily in the heart.[7]

Subtypes

protein gene aliases
GIRK1 KCNJ3 Kir3.1
GIRK2 KCNJ6 Kir3.2
GIRK3 KCNJ9 Kir3.3
GIRK4 KCNJ5 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, and sphingosine-1-phosphate receptors.[2][3]

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.[8][9] These are called muscarinic potassium channels (IKACh) and are heterotetramers composed of two GIRK1 and two GIRK4 subunits.[7][10]

References

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External links

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