Inward rectifier potassium channel 2.x (Kir2.x)

The Kir2.x subfamily of inward rectifier potassium channels, comprising Kir2.1, Kir2.2, Kir2.3, Kir2.4, and Kir2.6, represents a group of constitutively active channels that are fundamental to the electrical stability of excitable tissues [1, 9, 13]. These channels are primarily responsible for the inward rectifier potassium current (I_K1), which maintains the resting membrane potential and facilitates the final phase of action potential repolarization in cardiomyocytes, neurons, and skeletal muscle [3, 5, 7]. By allowing potassium ions to flow more easily into the cell than out, they prevent excessive loss of potassium during depolarization while stabilizing the cell at rest [7, 8]. Dysregulation or genetic mutations in Kir2.x channels are linked to several severe channelopathies, including Andersen-Tawil syndrome, Short QT syndrome, and thyrotoxic hypokalemic periodic paralysis [4, 5, 12, 14]. Pharmacologically, these channels are sensitive to various compounds, including antiarrhythmics like flecainide and propafenone, as well as experimental selective inhibitors like ML133 [1, 2, 6, 15]. Therapeutic modulation of Kir2.x activity is of significant interest for managing cardiac arrhythmias and potentially treating neuropathic pain or certain cancers, although the high homology between family members poses a challenge for isoform-specific drug development [2, 10, 11].

Other names

IRKKCNJ2KCNJ12KCNJ4KCNJ14KCNJ18Classical inward rectifier potassium channelI_K1 channel

Drugs targeting Kir2.x channels primarily act as pore blockers that occlude the ion conduction pathway [1, 6] or as activators (AgoKirs) that enhance outward potassium current by reducing spermine-mediated rectification or increasing the channel's affinity for phosphatidylinositol 4,5-bisphosphate (PIP2) [3, 5].