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Channels (Austin)
2011 Jan 01;53:269-79. doi: 10.4161/chan.5.3.15827.
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Kir4.1 K+ channels are regulated by external cations.
Edvinsson JM, Shah AJ, Palmer LG.
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The inwardly rectifying potassium channel (Kir), Kir4.1 mediates spatial K(+)-buffering in the CNS. In this process the channel is potentially exposed to a large range of extracellular K(+) concentrations ([K(+)]o). We found that Kir4.1 is regulated by K(+)o. Increased [K(+)]o leads to a slow (mins) increase in the whole-cell currents of Xenopus oocytes expressing Kir4.1. Conversely, removing K(+) from the bath solution results in a slow decrease of the currents. This regulation is not coupled to the pHi-sensitive gate of the channel, nor does it require the presence of K67, a residue necessary for K(+)o-dependent regulation of Kir1.1. The voltage-dependent blockers Cs(+) and Ba(2+) substitute for K(+) and prevent deactivation of the channel in the absence of K(+)o. Cs(+) blocks and regulates the channel with similar affinity, consistent with the regulatory sites being in the selectivity-filter of the channel. Although both Rb(+) and NH4(+) permeate Kir4.1, only Rb(+) is able to regulate the channel. We conclude that Kir4.1 is regulated by ions interacting with specific sites in the selectivity filter. Using a kinetic model of the permeation process we show the plausibility of the channel's sensing the extracellular ionic environment through changes in the selectivity occupancy pattern, and that it is feasible for an ion with the selectivity properties of NH4(+) to permeate the channel without inducing these changes.
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 Bernèche,
A microscopic view of ion conduction through the K+ channel.
2003,
Pubmed Bernèche,
Energetics of ion conduction through the K+ channel.
2001,
Pubmed Bockenhauer,
Epilepsy, ataxia, sensorineural deafness, tubulopathy, and KCNJ10 mutations.
2009,
Pubmed
,
Xenbase Chakrapani,
A quantitative description of KcsA gating I: macroscopic currents.
2007,
Pubmed Choe,
A conserved cytoplasmic region of ROMK modulates pH sensitivity, conductance, and gating.
1997,
Pubmed
,
Xenbase Choi,
Tetraethylammonium blockade distinguishes two inactivation mechanisms in voltage-activated K+ channels.
1991,
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 Cordero-Morales,
Voltage-dependent gating at the KcsA selectivity filter.
2006,
Pubmed 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 Doyle,
The structure of the potassium channel: molecular basis of K+ conduction and selectivity.
1998,
Pubmed Fakler,
Identification of a titratable lysine residue that determines sensitivity of kidney potassium channels (ROMK) to intracellular pH.
1996,
Pubmed
,
Xenbase Gao,
Activation-coupled inactivation in the bacterial potassium channel KcsA.
2005,
Pubmed Grabe,
K+ channel selectivity depends on kinetic as well as thermodynamic factors.
2006,
Pubmed
,
Xenbase Heinemann,
Ceiling of stimulus induced rises in extracellular potassium concentration in the cerebral cortex of cat.
1977,
Pubmed Hibino,
Inwardly rectifying potassium channels: their structure, function, and physiological roles.
2010,
Pubmed Higashi,
An inwardly rectifying K(+) channel, Kir4.1, expressed in astrocytes surrounds synapses and blood vessels in brain.
2001,
Pubmed Hoshi,
Two types of inactivation in Shaker K+ channels: effects of alterations in the carboxy-terminal region.
1991,
Pubmed
,
Xenbase Jiang,
The open pore conformation of potassium channels.
2002,
Pubmed Kofuji,
Potassium buffering in the central nervous system.
2004,
Pubmed Kucheryavykh,
Downregulation of Kir4.1 inward rectifying potassium channel subunits by RNAi impairs potassium transfer and glutamate uptake by cultured cortical astrocytes.
2007,
Pubmed Kutluay,
Rapid intracellular TEA block of the KcsA potassium channel.
2005,
Pubmed López-Barneo,
Effects of external cations and mutations in the pore region on C-type inactivation of Shaker potassium channels.
1993,
Pubmed
,
Xenbase Luzhkov,
K(+)/Na(+) selectivity of the KcsA potassium channel from microscopic free energy perturbation calculations.
2001,
Pubmed Neusch,
Lack of the Kir4.1 channel subunit abolishes K+ buffering properties of astrocytes in the ventral respiratory group: impact on extracellular K+ regulation.
2006,
Pubmed Olsen,
Functional expression of Kir4.1 channels in spinal cord astrocytes.
2006,
Pubmed Panyi,
Cross talk between activation and slow inactivation gates of Shaker potassium channels.
2006,
Pubmed Pearson,
Expression of a functional Kir4 family inward rectifier K+ channel from a gene cloned from mouse liver.
1999,
Pubmed
,
Xenbase Poopalasundaram,
Glial heterogeneity in expression of the inwardly rectifying K(+) channel, Kir4.1, in adult rat CNS.
2000,
Pubmed Rapedius,
H bonding at the helix-bundle crossing controls gating in Kir potassium channels.
2007,
Pubmed
,
Xenbase Rapedius,
Structural and functional analysis of the putative pH sensor in the Kir1.1 (ROMK) potassium channel.
2006,
Pubmed
,
Xenbase Reichold,
KCNJ10 gene mutations causing EAST syndrome (epilepsy, ataxia, sensorineural deafness, and tubulopathy) disrupt channel function.
2010,
Pubmed Sackin,
Regulation of ROMK by extracellular cations.
2001,
Pubmed
,
Xenbase Sackin,
Permeant cations and blockers modulate pH gating of ROMK channels.
2003,
Pubmed
,
Xenbase Sackin,
Structural locus of the pH gate in the Kir1.1 inward rectifier channel.
2005,
Pubmed
,
Xenbase Sackin,
An intersubunit salt bridge near the selectivity filter stabilizes the active state of Kir1.1.
2009,
Pubmed
,
Xenbase Sala-Rabanal,
Molecular mechanisms of EAST/SeSAME syndrome mutations in Kir4.1 (KCNJ10).
2010,
Pubmed Scholl,
Seizures, sensorineural deafness, ataxia, mental retardation, and electrolyte imbalance (SeSAME syndrome) caused by mutations in KCNJ10.
2009,
Pubmed Schulte,
pH-dependent gating of ROMK (Kir1.1) channels involves conformational changes in both N and C termini.
1998,
Pubmed
,
Xenbase 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 Schulte,
Gating of inward-rectifier K+ channels by intracellular pH.
2000,
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 Shi,
The EAST syndrome and KCNJ10 mutations.
2009,
Pubmed Somjen,
Ion regulation in the brain: implications for pathophysiology.
2002,
Pubmed Takumi,
A novel ATP-dependent inward rectifier potassium channel expressed predominantly in glial cells.
1995,
Pubmed
,
Xenbase Walz,
Role of astrocytes in the clearance of excess extracellular potassium.
2000,
Pubmed Xu,
A single residue contributes to the difference between Kir4.1 and Kir1.1 channels in pH sensitivity, rectification and single channel conductance.
2000,
Pubmed
,
Xenbase Yang,
Opposite effects of pH on open-state probability and single channel conductance of kir4.1 channels.
1999,
Pubmed
,
Xenbase Zhang,
Localization of the pH gate in Kir1.1 channels.
2006,
Pubmed
,
Xenbase Zhou,
The occupancy of ions in the K+ selectivity filter: charge balance and coupling of ion binding to a protein conformational change underlie high conduction rates.
2003,
Pubmed Zhou,
Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution.
2001,
Pubmed
