Referenced in: none

Automatically associated channels: Kir1.1 , Kir2.1

Title: Extracellular K+ and intracellular pH allosterically regulate renal Kir1.1 channels.

Authors: T Doi, B Fakler, J H Schultz, U Schulte, U Brandle, S Weidemann, H P Zenner, F Lang, J P Ruppersberg

Journal, date & volume: J. Biol. Chem., 1996 Jul 19 , 271, 17261-6

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/8663367

Abstract
The channels that control K+ homeostasis by mediating K+ secretion across the apical membrane of renal tubular cells have recently been cloned and designated ROMK1, -2, and -3. Native apical K+ channels are indirectly regulated by the K+ concentration at the basolateral membrane through a cascade of intracellular second messengers. It is shown here that ROMK1 (Kir1.1) channels are also directly regulated by the extracellular (apical) K+ concentration, and that this K+ regulation is coupled to intracellular pH. The K+ regulation and its coupling to pH were assigned to different structural parts of the channel protein. K+ regulation is determined by the core region, which comprises the two hydrophobic segments M1 and M2 and the P region. Decoupling from pH was achieved by exchanging the N terminus of ROMK1 by that of the pH-insensitive channel IRK1 (Kir2.1). These results suggest an allosteric regulation of ROMK1 channels by extracellular K+ and intracellular pH, which may represent a novel link between K+ homeostasis and pH control.