Homotetramers of Kir 1.1 function as inwardly rectifying potassium transport channels. Ki 1.1 are found on the apical side of the cells in the ascending limp of loop of henle and upon activation transport K+ into the extracellular space. Heterotetramers of Kir 4.1 and Ki 5.1 are found on the basolateral side of cells in the distal convoluted tube. Activation of kir 4.1 and 5.1 heterotetramers leads to efflux of K+ into the extracellular space.
inward rectifier potassium channel activity of Potassium transport channels (Kir 1.1 and Kir 4.1/5.1) [plasma membrane]