Kir3.4: Proteins and Enzymes

G-protein regulated inward-rectifier potassium channels (GIRK) are part of a superfamily of inward-rectifier K+ channels. To date four GIRK subunits, designated GIRK1-4 (also designated Kir3.1-4), have been identified in mammals, and GIRK5 has been found in Xenopus oocytes. GIRK channels exist in vivo both as homotetramers and heterotetramers. GIRK channels are modulated by G-proteins; they are also modulated by phosphatidylinositol 4,5-bisphosphate, intracellular sodium, ethanol and mechanical stretch. GIRK1, 2 and 3 are highly abundant in brain. In general, neuronal GIRK channels are involved in the regulation of the excitability of neurons and may contribute to the resting potential.