Channelpedia

Kir4.1

Description: potassium inwardly-rectifying channel, subfamily J, member 10
Gene: Kcnj10     Synonyms: Kir4.1, kcnj10, BIR10, BIRK-1

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Introduction


Experimental data


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Gene

RGD ID Chromosome Position Species
61822 13 88341102-88370591 Rat
62113 1 174271341-174304216 Mouse
731912 1 160007257-160040051 Human

Kcnj10 : potassium inwardly-rectifying channel, subfamily J, member 10


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Transcript

Acc No Sequence Length Source
NM_031602 n/A n/A NCBI
NM_001039484 n/A n/A NCBI
NM_002241 n/A n/A NCBI

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Ontology

Accession Name Definition Evidence
GO:0016021 integral to membrane Penetrating at least one phospholipid bilayer of a membrane. May also refer to the state of being buried in the bilayer with no exposure outside the bilayer. When used to describe a protein, indicates that all or part of the peptide sequence is embedded in the membrane. IEA
GO:0016020 membrane Double layer of lipid molecules that encloses all cells, and, in eukaryotes, many organelles; may be a single or double lipid bilayer; also includes associated proteins. IEA

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Interaction

Tricyclic antidepressants (TCAs) influence the astroglial Kir4.1 channels expressed in HEK293T cells. Su et al. [202] demonstrated that nortriptyline and other TCAs, including amitriptyline, desipramine, and imipramine, inhibit homomeric Kir4.1 channels in a voltage- and time-dependent fashion.

Unlike other Kir family members, heteromultimerization of inter-subfamily members Kir4.1 and Kir5.1 leads to a channel with distinct functional properties (Casamassima[1018], Konstas [1019], Pessia [1020], Tanemoto [1013], Tucker [1021], Xu [1022], Yang [1023]). Of particular interest in these newly emerging properties is the enhanced sensitivity to intracellular pH (pKa 7.45), allowing the heteromeric Kir4.1–Kir5.1 channel to detect pH changes at physiological levels (Pessia [1020], Xu [1022], Yang [1023], Xui [1024]).


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Protein


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Structure


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Distribution

Kir4.1 alone exists at the end-feet of retinal Mueller cells, and both Kir4.1 and Kir5.1, are detected in the cell body (Ishii [1010]).


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Expression

It was shown that, among them, Kir4.1 and Kir5.1 are expressed predominantly in brain astrocytes and retinal Muller cells (Takumi et al., 1995 [1009]; Ishii et al., 1997 [1010], 2003; Poopalasundaram et al., 2000 [1011]; Hibino et al., 2004 [1012]).

The Kir4.1 and Kir5.1 subunits are expressed in the proximal convoluted tubule, the distal convoluted tubule and the cortical collecting duct of the kidney (Tucker [1019], Tanemoto [1013], Tanemoto [1027]).


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Functional

Astroglial Kir channels are either homotetramers of Kir4.1 or heterotetramers of Kir4.1 and Kir5.1, both of which constitutively allow large inward K+ currents at potentials negative to EK and small, but significant, outward K+ currents at those positive to EK (Takumi et al., 1995 [1009]; Ishii et al., 1997 [1010]; Tanemoto et al., 2000 [1013]; Higashi et al., 2001 [1014]). Thus, depending on the difference between local EK and the membrane potential of astrocytes, these Kir channels can mediate either absorption or extrusion of K+ across the astroglial cell membrane and thus can act as the spatial K+-buffering current. (Su [202])

In addition, Kir4.1 channel and the water channel, aquaporin-4, are colocalized in certain membrane domains of brain astrocytes and Muller cells, suggesting that spatial K+ buffering may couple with water movement across the astroglial membrane (Nagelhus et al., 1999 [1015]; Amiry-Moghaddam et al., 2003 [1016]; Puwarawuttipanit et al., 2006 [1017]).

Kir4.1 and Kir5.1 subunits are expressed in the kidney, eye and brainstem suggests that the channel may be a candidate molecule for the regulation of K+ homeostasis and central CO2 chemoreception (Pessia [1020], Yang [1023], Jiang [1025], Wu [1026]).


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Kinetics


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Model


References

203

Rojas A. et al. Protein kinase C dependent inhibition of the heteromeric Kir4.1-Kir5.1 channel.
Biochim. Biophys. Acta, 2007 Sep , 1768 (2030-42).

Hibino H. et al. Differential expression and distribution of Kir5.1 and Kir4.1 inwardly rectifying K+ channels in retina.
Am. J. Physiol., Cell Physiol., 2003 Aug , 285 (C260-7).

Kurachi Y. et al. In vivo formation of a proton-sensitive K+ channel by heteromeric subunit assembly of Kir5.1 with Kir4.1.
J. Physiol. (Lond.), 2000 Jun 15 , 525 Pt 3 (587-92).

Amiry-Moghaddam M. et al. An alpha-syntrophin-dependent pool of AQP4 in astroglial end-feet confers bidirectional water flow between blood and brain.
Proc. Natl. Acad. Sci. U.S.A., 2003 Feb 18 , 100 (2106-11).

Tucker SJ. et al. Identification of domains that control the heteromeric assembly of Kir5.1/Kir4.0 potassium channels.
Am. J. Physiol., Cell Physiol., 2003 Apr , 284 (C910-7).

Xu H. et al. Modulation of kir4.1 and kir5.1 by hypercapnia and intracellular acidosis.
J. Physiol. (Lond.), 2000 May 1 , 524 Pt 3 (725-35).

Tanemoto M. et al. PDZ binding motif-dependent localization of K+ channel on the basolateral side in distal tubules.
Am. J. Physiol. Renal Physiol., 2004 Dec , 287 (F1148-53).


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Credits