G protein-coupled inwardly-rectifying potassium channel

potassium inwardly-rectifying channel, subfamily J, member 9
Identifiers
Symbol	KCNJ9
Alt. symbols	Kir3.3, GIRK3
IUPHAR	436
NCBI gene	3765
HGNC	6270
OMIM	600932
RefSeq	NM_004983
UniProt	Q92806
Other data
Locus	Chr. 1 q23.2

potassium inwardly-rectifying channel, subfamily J, member 6
Identifiers
Symbol	KCNJ6
Alt. symbols	KCNJ7, Kir3.2, GIRK2, KATP2, BIR1, hiGIRK2
IUPHAR	435
NCBI gene	3763
HGNC	6267
OMIM	600877
RefSeq	NM_002240
UniProt	P48051
Other data
Locus	Chr. 21 q22.1

potassium inwardly-rectifying channel, subfamily J, member 3
Identifiers
Symbol	KCNJ3
Alt. symbols	Kir3.1, GIRK1, KGA
IUPHAR	434
NCBI gene	3760
HGNC	6264
OMIM	601534
RefSeq	NM_002239
UniProt	P48549
Other data
Locus	Chr. 2 q24.1

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).[1][2] GPCRs in turn release activated G-protein βγ- subunits (G_βγ) from inactive heterotrimeric G protein complexes (G_αβγ). Finally, the G_βγ 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 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.

potassium inwardly-rectifying channel, subfamily J, member 5
Identifiers
Symbol	KCNJ5
Alt. symbols	Kir3.4, CIR, KATP1, GIRK4
IUPHAR	437
NCBI gene	3762
HGNC	6266
OMIM	600734
RefSeq	NM_000890
UniProt	P48544
Other data
Locus	Chr. 11 q24

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	K_ir3.1
GIRK2	KCNJ6	K_ir3.2
GIRK3	KCNJ9	K_ir3.3
GIRK4	KCNJ5	K_ir3.4

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-HT_1A serotonin, somatostatin, galanin, m-Glu, GABA_B, TAAR1, CB₁ and CB₂, and sphingosine-1-phosphate receptors.[2][3][8]

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.[9][10] These are called muscarinic potassium channels (I_KACh) and are heterotetramers composed of two GIRK1 and two GIRK4 subunits.[7][11]

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References

Dascal N (1997). "Signalling via the G protein-activated K⁺ channels". Cell. Signal. 9 (8): 551–73. doi:10.1016/S0898-6568(97)00095-8. PMID 9429760.
Yamada M, Inanobe A, Kurachi Y (December 1998). "G protein regulation of potassium ion channels". Pharmacological Reviews. 50 (4): 723–60. PMID 9860808.
Ledonne A, Berretta N, Davoli A, Rizzo GR, Bernardi G, Mercuri NB (2011). "Electrophysiological effects of trace amines on mesencephalic dopaminergic neurons". Front Syst Neurosci. 5: 56. doi:10.3389/fnsys.2011.00056. PMC 3131148. PMID 21772817. inhibition of firing due to increased release of dopamine; (b) reduction of D2 and GABAB receptor-mediated inhibitory responses (excitatory effects due to disinhibition); and (c) a direct TA1 receptor-mediated activation of GIRK channels which produce cell membrane hyperpolarization.
Kobayashi T, Ikeda K, Ichikawa T, Abe S, Togashi S, Kumanishi T (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. 208 (3): 1166–73. doi:10.1006/bbrc.1995.1456. PMID 7702616.
Karschin C, Dissmann E, Stühmer W, Karschin A (June 1996). "IRK(1-3) and GIRK(1-4) inwardly rectifying K+ channel mRNAs are differentially expressed in the adult rat brain". J. Neurosci. 16 (11): 3559–70. doi:10.1523/JNEUROSCI.16-11-03559.1996. PMC 6578832. PMID 8642402.
Chen SC, Ehrhard P, Goldowitz D, Smeyne RJ (December 1997). "Developmental expression of the GIRK family of inward rectifying potassium channels: implications for abnormalities in the weaver mutant mouse". Brain Res. 778 (2): 251–64. doi:10.1016/S0006-8993(97)00896-2. PMID 9459542.
Krapivinsky G, Gordon EA, Wickman K, Velimirović B, Krapivinsky L, Clapham DE (1995). "The G-protein-gated atrial K⁺ channel I_KACh is a heteromultimer of two inwardly rectifying K⁺-channel proteins". Nature. 374 (6518): 135–41. doi:10.1038/374135a0. PMID 7877685.
Svízenská I, Dubový P, Sulcová A (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. 90 (4): 501–11. doi:10.1016/j.pbb.2008.05.010. PMID 18584858.
Kunkel MT, Peralta EG (1995). "Identification of domains conferring G protein regulation on inward rectifier potassium channels". Cell. 83 (3): 443–9. doi:10.1016/0092-8674(95)90122-1. PMID 8521474.
Wickman K, Krapivinsky G, Corey S, Kennedy M, Nemec J, Medina I, Clapham DE (1999). "Structure, G protein activation, and functional relevance of the cardiac G protein-gated K⁺ channel, I_KACh". Ann. N. Y. Acad. Sci. 868 (1): 386–98. doi:10.1111/j.1749-6632.1999.tb11300.x. PMID 10414308. Archived from the original on 2006-01-29. Retrieved 2008-02-03.
Corey S, Krapivinsky G, Krapivinsky L, Clapham DE (1998). "Number and stoichiometry of subunits in the native atrial G-protein-gated K⁺ channel, I_KACh". J. Biol. Chem. 273 (9): 5271–8. doi:10.1074/jbc.273.9.5271. PMID 9478984.

External links

G+Protein-Coupled+Inwardly-Rectifying+Potassium+Channels at the US National Library of Medicine Medical Subject Headings (MeSH)

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[pmid9429760-1] Dascal N (1997). "Signalling via the G protein-activated K⁺ channels". Cell. Signal. 9 (8): 551–73. doi:10.1016/S0898-6568(97)00095-8. PMID 9429760.

[pmid9860808-2] Yamada M, Inanobe A, Kurachi Y (December 1998). "G protein regulation of potassium ion channels". Pharmacological Reviews. 50 (4): 723–60. PMID 9860808.

[GIRK-3] Ledonne A, Berretta N, Davoli A, Rizzo GR, Bernardi G, Mercuri NB (2011). "Electrophysiological effects of trace amines on mesencephalic dopaminergic neurons". Front Syst Neurosci. 5: 56. doi:10.3389/fnsys.2011.00056. PMC 3131148. PMID 21772817. inhibition of firing due to increased release of dopamine; (b) reduction of D2 and GABAB receptor-mediated inhibitory responses (excitatory effects due to disinhibition); and (c) a direct TA1 receptor-mediated activation of GIRK channels which produce cell membrane hyperpolarization.

[pmid7702616-4] Kobayashi T, Ikeda K, Ichikawa T, Abe S, Togashi S, Kumanishi T (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. 208 (3): 1166–73. doi:10.1006/bbrc.1995.1456. PMID 7702616.

[pmid8642402-5] Karschin C, Dissmann E, Stühmer W, Karschin A (June 1996). "IRK(1-3) and GIRK(1-4) inwardly rectifying K+ channel mRNAs are differentially expressed in the adult rat brain". J. Neurosci. 16 (11): 3559–70. doi:10.1523/JNEUROSCI.16-11-03559.1996. PMC 6578832. PMID 8642402.

[pmid9459542-6] Chen SC, Ehrhard P, Goldowitz D, Smeyne RJ (December 1997). "Developmental expression of the GIRK family of inward rectifying potassium channels: implications for abnormalities in the weaver mutant mouse". Brain Res. 778 (2): 251–64. doi:10.1016/S0006-8993(97)00896-2. PMID 9459542.

[pmid7877685-7] Krapivinsky G, Gordon EA, Wickman K, Velimirović B, Krapivinsky L, Clapham DE (1995). "The G-protein-gated atrial K⁺ channel I_KACh is a heteromultimer of two inwardly rectifying K⁺-channel proteins". Nature. 374 (6518): 135–41. doi:10.1038/374135a0. PMID 7877685.

[8] Svízenská I, Dubový P, Sulcová A (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. 90 (4): 501–11. doi:10.1016/j.pbb.2008.05.010. PMID 18584858.

[pmid8521474-9] Kunkel MT, Peralta EG (1995). "Identification of domains conferring G protein regulation on inward rectifier potassium channels". Cell. 83 (3): 443–9. doi:10.1016/0092-8674(95)90122-1. PMID 8521474.

[pmid10414308-10] Wickman K, Krapivinsky G, Corey S, Kennedy M, Nemec J, Medina I, Clapham DE (1999). "Structure, G protein activation, and functional relevance of the cardiac G protein-gated K⁺ channel, I_KACh". Ann. N. Y. Acad. Sci. 868 (1): 386–98. doi:10.1111/j.1749-6632.1999.tb11300.x. PMID 10414308. Archived from the original on 2006-01-29. Retrieved 2008-02-03.

[pmid9478984-11] Corey S, Krapivinsky G, Krapivinsky L, Clapham DE (1998). "Number and stoichiometry of subunits in the native atrial G-protein-gated K⁺ channel, I_KACh". J. Biol. Chem. 273 (9): 5271–8. doi:10.1074/jbc.273.9.5271. PMID 9478984.