Examples of KCNQ1-KCNE2 location and function in polarized epithelia. (a) Left, representation of a gastric gland; right, the gastric /-ATPase requires a luminal recycling pathway for proton secretion and gastric acidification, formed by complexes of KCNQ1 (Q1) and KCNE2 (E2). (b) Left, representation of a thyroid follicle skirted by thyroid epithelial cells (thyrocytes); right, thyroid hormone ( and ) biosynthesis requires to pass across the thyrocyte from the blood into the colloid, where it is oxidized and organified by incorporation into thyroglobulin (iodination and conjugation). Channels formed by a complex of KCNQ1 and KCNE2, on the thyrocyte basolateral membrane, facilitate efficient function of the basolateral sodium iodide symporter (NIS). (c) Left, representation of the choroid plexus epithelium (CPe); right, KCNQ1 is regulated by KCNE2 in the CPe apical membrane.
