Inward-rectifier potassium ion channel
（重定向自Inwardly rectifying potassium channel）
![](/Images/godic/202501/20/PDB_1p7b_EBI0248.jpg")
![Figure 1. Whole-cell current recordings of Kir2 inwardly-rectifying potassium channels expressed in an HEK293 cell. (This is a strongly inwardly rectifying current. Downward deflections are inward currents, upward deflections outward currents, and the x-axis is time in seconds.) There are 13 responses superimposed in this image. The bottom-most trace is current elicited by a voltage step to negative 60mV, and the top-most to positive 60mV, relative to the resting potential, which is close to the K+ reversal potential in this experimental system. Other traces are in 10mV increments between the two.](/Images/godic/202501/20/Inward-rectification0248.png")
Inwardly rectifying potassium channels (Kir, IRK) are a specific subset of potassium (K) selective ion channels. To date, seven subfamilies have been identified in various mammalian cell types, plants, and bacteria. They are the targets of multiple toxins, and malfunction of the channels has been implicated in several diseases. IRK channels possess a pore domain, homologous to that of voltage-gated ion channels, and flanking transmembrane segments (TMSs). They may exist in the membrane as homo- or heterooligomers and each monomer possesses between 2 and 4 TMSs. In terms of function, these proteins transport potassium (K), with a greater tendency for K uptake than K export.