Immunolocalization of an inwardly rectifying K+ channel, K-AB-2 (Kir4.1), in the basolateral membrane of renal distal tubular epithelia

Immunolocalization of K-AB-2 (Kir4.1), an inwardly rectifying K+ channel with a putative ATP-binding domain, was examined in rat kidney where expression of K-AB-2 mRNA was previously shown, Anti-K-AB-2 antibody was raised in rabbit and then affinity-purified. An immunohistochemical study revealed that K-AB-2 immunoreactivity was detected specifically in the basolateral membrane of distal tubular epithelia, Therefore, K-AB-2 is the first K+ channel shown to be localized in the basolateral membrane of renal epithelia, The finding suggests that K-AB-2 may contribute to supplying K+ to the Na+-K+ pump, which is abundant in the basolateral membrane of distal tubular epithelia, as well as to maintenance of the deep negative membrane potential of these cells.