Polarized targeting of a Shaker-like (A-type) K+-channel in the polarized epithelial cell line MDCK

Abstract

Functional K_v 1.4 channels were stably expressed in filter-grown MDCK cells which form a polarized epithelium with two distinct plasma membrane domains: a basolateral and an apical cell surface. The Shaker-related K_v 1.4 channels mediated in MDCK cells fast transient (A-type) voltage-activated outward currents having similar properties to the ones reported for K_v 1.4 in the Xenopus oocytes expression system. Immunoblot analysis with specific anti-K_v 1.4 antibodies showed that two K_v 1.4 protein forms are expressed in MDCK cells which most likely represent the glycosylated and non-glycosylated K_v 1.4 protein, respectively. Using immunocytochemistry and confocal microscopy we showed that the K_v 1.4 channels are specifically localized in the basolateral membranes of MDCK cells. Thus, the MDCK cells may provide an important model system to analyse the polarized transport of ion channels such as K_v 1.4, which are distinctly expressed in the mammalian central nervous system.