G protein-activated inward rectifier potassium channel (GIRK)

G protein-activated inward rectifier potassium (GIRK) channels, also known as Kir3 channels, are a family of inwardly rectifying potassium channels that serve as critical effectors for various G protein-coupled receptors (GPCRs). These channels are directly activated by the Gβγ subunits of Gi/o proteins, allowing potassium ions to flow out of the cell and causing membrane hyperpolarization, which inhibits cellular activity [1][2]. In the cardiovascular system, GIRK1/GIRK4 heteromers (IKACh) are activated by acetylcholine to slow the heart rate, and their overactivity is linked to atrial fibrillation [3]. In the brain, GIRK channels (comprising GIRK1, GIRK2, and GIRK3) mediate the inhibitory effects of neurotransmitters like GABA, dopamine, and opioids, playing roles in pain modulation, reward pathways, and seizure prevention [1][4]. Mutations in the KCNJ5 gene (GIRK4) are a well-documented cause of primary aldosteronism and secondary hypertension due to loss of channel selectivity and subsequent sodium influx in the adrenal cortex [5]. Therapeutic strategies currently focus on developing selective GIRK inhibitors for treating cardiac arrhythmias and primary aldosteronism, as well as modulators for neurological and psychiatric disorders [2][4]. Sources: [1] Lüscher, C., & Slesinger, P. A. (2010). "Emerging roles for G protein-gated inwardly rectifying potassium (GIRK) channels in health and disease." Nature Reviews Neuroscience. [2] Hibino, H., et al. (2010). "Inwardly Rectifying Potassium Channels: Their Structure, Function, and Physiological Roles." Physiological Reviews. [3] Ehrlich, J. R. (2008). "Inward rectifier potassium channels as a target for antiarrhythmic drug development." Current Opinion in Drug Discovery & Development. [4] Rifkin, R. A., et al. (2017). "G protein-gated inwardly rectifying potassium (GIRK) channels: A potential target for the treatment of chronic pain." Channels. [5] Choi, M., et al. (2011). "K+ channel mutations in adrenal aldosterone-producing adenomas and hereditary hypertension." Science.

Other names

Kir3 channelG protein-gated inwardly rectifying potassium channelKCNJ channelG protein-coupled inwardly rectifying potassium channel

Direct activation by the G-beta-gamma (Gβγ) subunits of heterotrimeric G proteins following the stimulation of G protein-coupled receptors (GPCRs), leading to potassium efflux and cellular hyperpolarization; pharmacological agents may either block these channels to increase excitability (e.g., in cardiac arrhythmia) or modulate them to restore normal signaling.