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J Physiol
2011 Dec 15;589Pt 24:5949-63. doi: 10.1113/jphysiol.2011.220731.
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Potassium-dependent activation of Kir4.2 K⁺ channels.
Edvinsson JM
,
Shah AJ
,
Palmer LG
.
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The inwardly rectifying potassium channel Kir4.2 is sensitive to changes in the extracellular potassium concentration ([K(+)](o)). This form of regulation is manifest as a slow (tens of minutes) increase in the whole-cell currents when [K(+)](o) is increased. Here we have investigated the mechanism of K(o)(+) sensitivity of Kir4.2 expressed in Xenopus oocytes. Using two-electrode voltage clamp we found that the sensitivity is specific for the homomeric form of the channel and is completely abolished when coexpressed with Kir5.1. Furthermore, unlike Kir1.1, there is no coupling between the intracellular pH sensitivity and K(o)(+) sensitivity, as is evident by introducing a mutation (K66M), which greatly decreases the pH(i) sensitivity while the K(o)(+) sensitivity remains unchanged. K(o)(+)-dependent activation of Kir4.2 does not involve an increase in the surface expression of the channel, nor is there a difference in the open probability between high and low [K(+)] as determined through patch-clamp measurements. We also found that there is an inverse relationship between the rates of both activation and deactivation and [K(+)](o). Using a kinetic model we argue that Kir4.2 exists in at least three states at the plasma membrane: a deactivated state, an intermediate unstable state and an active state, and that [K(+)](o) affects the rate of transition from the intermediate state to the active state.
Baukrowitz,
Modulation of K+ current by frequency and external [K+]: a tale of two inactivation mechanisms.
1995, Pubmed
Baukrowitz,
Modulation of K+ current by frequency and external [K+]: a tale of two inactivation mechanisms.
1995,
Pubmed
Bernèche,
A gate in the selectivity filter of potassium channels.
2005,
Pubmed
Chakrapani,
A quantitative description of KcsA gating I: macroscopic currents.
2007,
Pubmed
Chakrapani,
A quantitative description of KcsA gating II: single-channel currents.
2007,
Pubmed
Choe,
A conserved cytoplasmic region of ROMK modulates pH sensitivity, conductance, and gating.
1997,
Pubmed
,
Xenbase
Clarke,
Domain reorientation and rotation of an intracellular assembly regulate conduction in Kir potassium channels.
2010,
Pubmed
Cordero-Morales,
Molecular determinants of gating at the potassium-channel selectivity filter.
2006,
Pubmed
Cordero-Morales,
Molecular driving forces determining potassium channel slow inactivation.
2007,
Pubmed
,
Xenbase
Cuello,
Structural mechanism of C-type inactivation in K(+) channels.
2010,
Pubmed
Cuello,
Structural basis for the coupling between activation and inactivation gates in K(+) channels.
2010,
Pubmed
Dahlmann,
Regulation of Kir channels by intracellular pH and extracellular K(+): mechanisms of coupling.
2004,
Pubmed
,
Xenbase
Doi,
Extracellular K+ and intracellular pH allosterically regulate renal Kir1.1 channels.
1996,
Pubmed
,
Xenbase
Domene,
Conformational changes and gating at the selectivity filter of potassium channels.
2008,
Pubmed
Edvinsson,
Kir4.1 K+ channels are regulated by external cations.
2011,
Pubmed
,
Xenbase
Fakler,
Identification of a titratable lysine residue that determines sensitivity of kidney potassium channels (ROMK) to intracellular pH.
1996,
Pubmed
,
Xenbase
Gupta,
Conformational changes during the gating of a potassium channel revealed by structural mass spectrometry.
2010,
Pubmed
Haj-Yasein,
Evidence that compromised K+ spatial buffering contributes to the epileptogenic effect of mutations in the human Kir4.1 gene (KCNJ10).
2011,
Pubmed
Harris,
A novel neutrophil elastase inhibitor prevents elastase activation and surface cleavage of the epithelial sodium channel expressed in Xenopus laevis oocytes.
2007,
Pubmed
,
Xenbase
Hibino,
Inwardly rectifying potassium channels: their structure, function, and physiological roles.
2010,
Pubmed
Hill,
Cloning, expression, and localization of a rat hepatocyte inwardly rectifying potassium channel.
2002,
Pubmed
Hoshi,
Two types of inactivation in Shaker K+ channels: effects of alterations in the carboxy-terminal region.
1991,
Pubmed
,
Xenbase
Lam,
Modulation of Kir4.2 rectification properties and pHi-sensitive run-down by association with Kir5.1.
2006,
Pubmed
López-Barneo,
Effects of external cations and mutations in the pore region on C-type inactivation of Shaker potassium channels.
1993,
Pubmed
,
Xenbase
Massaeli,
Extracellular K+ is a prerequisite for the function and plasma membrane stability of HERG channels.
2010,
Pubmed
Pearson,
Expression of a functional Kir4 family inward rectifier K+ channel from a gene cloned from mouse liver.
1999,
Pubmed
,
Xenbase
Rapedius,
Structural and functional analysis of the putative pH sensor in the Kir1.1 (ROMK) potassium channel.
2006,
Pubmed
,
Xenbase
Rapedius,
H bonding at the helix-bundle crossing controls gating in Kir potassium channels.
2007,
Pubmed
,
Xenbase
Rapedius,
Control of pH and PIP2 gating in heteromeric Kir4.1/Kir5.1 channels by H-Bonding at the helix-bundle crossing.
2007,
Pubmed
Sackin,
Permeant cations and blockers modulate pH gating of ROMK channels.
2003,
Pubmed
,
Xenbase
Sackin,
Potassium-dependent slow inactivation of Kir1.1 (ROMK) channels.
2004,
Pubmed
,
Xenbase
Sackin,
Structural locus of the pH gate in the Kir1.1 inward rectifier channel.
2005,
Pubmed
,
Xenbase
Sackin,
Role of conserved glycines in pH gating of Kir1.1 (ROMK).
2006,
Pubmed
,
Xenbase
Sackin,
External K activation of Kir1.1 depends on the pH gate.
2007,
Pubmed
Sackin,
An intersubunit salt bridge near the selectivity filter stabilizes the active state of Kir1.1.
2009,
Pubmed
,
Xenbase
Sackin,
Regulation of ROMK by extracellular cations.
2001,
Pubmed
,
Xenbase
Schulte,
pH gating of ROMK (K(ir)1.1) channels: control by an Arg-Lys-Arg triad disrupted in antenatal Bartter syndrome.
1999,
Pubmed
Schulte,
K(+)-dependent gating of K(ir)1.1 channels is linked to pH gating through a conformational change in the pore.
2001,
Pubmed
,
Xenbase
Shuck,
Cloning and characterization of two K+ inward rectifier (Kir) 1.1 potassium channel homologs from human kidney (Kir1.2 and Kir1.3).
1997,
Pubmed
,
Xenbase
Yellen,
The moving parts of voltage-gated ion channels.
1998,
Pubmed
Zhang,
Localization of the pH gate in Kir1.1 channels.
2006,
Pubmed
,
Xenbase
