The structural domains contributing to ion permeation and selectivity in K channels were examined in inward-rectifier K(+) channels ROMK2 (Kir1.1b), IRK1 (Kir2.1), and their chimeras using heterologous expression in Xenopus oocytes. Patch-clamp recordings of single channels were obtained in the cell-attached mode with different permeant cations in the pipette. For inward K(+) conduction, replac...

Abstract The S362A mutation block ROMK2 (Kir1.1b) endocytosis in Xenopus laevis oocyte membrane . Saeed Hajihashemi1 , 1-Assistant professor, PhD in Physiology, Department of Physiology, School of Medical science, Arak University of Medical Sciences. Introduction: ROMK channel is localized on the apical membrane of the nephron. Recent studies suggest that endocytosis of ROMK chan...

introduction: recent studies suggest that endocytosis of romk channels is important for regulation of k+ secretion in cortical collecting ducts. in this study the effect of v364d mutation is examined on the membrane turnover and stability of romk2 channel when expressing in xenopus laevis oocytes. materials and methods: in this experimental study, oocytes were isolated by standard protocols usi...

ROMK channels play a key role in overall K balance by controlling K secretion across the apical membrane of mammalian cortical collecting tubule. In contrast to the family of strong inward rectifiers (IRKs), ROMK channels are markedly sensitive to intracellular pH. Using Xenopus oocytes, we have confirmed this pH sensitivity at both the single-channel and whole cell level. Reduction of oocyte p...

We have previously demonstrated that the ROMK channel maintains the property of arachidonic acid (AA) sensitivity observed originally in the native ATP-sensitive K+channel of the rat cortical collecting duct (16). We used the patch-clamp technique to extend these studies to other NH2-terminal splice variants of the ROMK channel family, ROMK2 and ROMK3, expressed in Xenopus oocytes to determine ...

ROMK channels are regulated by internal pH (pH(i)) and extracellular K(+) (K(+)(o)). The mechanisms underlying this regulation were studied in these channels after expression in Xenopus oocytes. Replacement of the COOH-terminal portion of ROMK2 (Kir1.1b) with the corresponding region of the pH-insensitive channel IRK1 (Kir 2.1) produced a chimeric channel (termed C13) with enhanced sensitivity ...

Previous studies suggested that the cytoplasmic COOH-terminal portions of inward rectifier K channels could contribute significant resistance barriers to ion flow. To explore this question further, we exchanged portions of the COOH termini of ROMK2 (Kir1.1b) and IRK1 (Kir2.1) and measured the resulting single-channel conductances. Replacing the entire COOH terminus of ROMK2 with that of IRK1 de...