We demonstrate here that coexpression of ROMK2, an inwardly rectifying ATP-sensitive renal K+ channel (IKATP) with cystic fibrosis transmembrane regulator (CFTR) significantly enhances the sensitivity of ROMK2 to the sulfonylurea compound glibenclamide. When expressed alone, ROMK2 is relatively insensitive to glibenclamide. The interaction between ROMK2, CFTR, and glibenclamide is modulated by ...

In a previous study on inside-out patches of Xenopus oocytes, we demonstrated that the cystic fibrosis transmembrane conductance regulator (CFTR) enhances the glibenclamide sensitivity of a coexpressed inwardly rectifying K+ channel, ROMK2 (C. M. McNicholas, W. B. Guggino, E. M. Schwiebert, S. C. Hebert, G. Giebisch, and M. E. Egan. Proc. Natl. Acad. Sci. USA 93: 8083-8088, 1996). In the presen...

The activity of the cloned renal K+ channel (ROMK2) is dependent on a balance between phosphorylation and dephosphorylation. There are only three protein kinase A (PKA) sites on ROMK2, with the phosphorylated residues being serine-25 (S25), serine-200 (S200), and serine-294 (S294) (Z.-C. Xu, Y. Yang, and S. C. Hebert. J. Biol. Chem. 271: 9313-9319, 1996). We previously mutated these sites from ...

Recent studies showed that coexpression of Kir6.1 or Kir6.2 with the sulfonylurea receptor (SUR1, SUR2A, or SUR2B) reconstituted an inwardly rectifying, ATP-sensitive K(+) channel that was inhibited by glibenclamide (2, 15-17). Here we report the isolation of a rat homolog of mouse SUR2B (denoted rSUR2B) from a rat kidney cDNA library. The rSUR2B sequence contains a 4,635-bp open reading frame ...

MacGregor, Gordon G., Jason Z. Xu, Carmel M. McNicholas, Gerhard Giebisch, and Steven C. Hebert. Partially active channels produced by PKA site mutation of the cloned renal K1 channel, ROMK2 (kir1.2). Am. J. Physiol. 275 (Renal Physiol. 44): F415–F422, 1998.—The activity of the cloned renal K1 channel (ROMK2) is dependent on a balance between phosphorylation and dephosphorylation. There are onl...

pH is an important modulator of the low-conductance ATP-sensitive K+ channel of the distal nephron. To examine the mechanism of interaction of protons with the channel-forming protein, we expressed the cloned renal K channel, ROMK (Kir1.x), in Xenopus oocytes and examined the response to varied concentrations of protons both in the presence and in the absence of ATP. Initial experiments were pe...

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...