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.78 These are called muscarinic potassium channels (IKACh) and are heterotetramers composed of two GIRK1 and two GIRK4 subunits.69
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^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. PMID8642402.
^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. PMID9459542.
^ abKrapivinsky G, Gordon EA, Wickman K, Velimirović B, Krapivinsky L, Clapham DE (March 1995). "The G-protein-gated atrial K+ channel IKACh is a heteromultimer of two inwardly rectifying K(+)-channel proteins". Nature374 (6518): 135–41. doi:10.1038/374135a0. PMID7877685.
^Corey S, Krapivinsky G, Krapivinsky L, Clapham DE (1998). "Number and stoichiometry of subunits in the native atrial G-protein-gated K+ channel, IKACh". J. Biol. Chem.273 (9): 5271–8. doi:10.1074/jbc.273.9.5271. PMID9478984.