Inward-rectifying potassium channel. Homodimer. Each of the two pore-forming region (also called P-domain or P-loop) is enclosed by two transmembrane segments (2P/4TM) and contains the GYGD signature motif which seems to be involved in potassium selectivity. Belongs to the two pore domain potassium channel (TC 1.A.1.7) family.