Channelpedia

Kir4.1

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

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Introduction

The Kir channel family comprises more than 15 members that fall into seven subfamilies (Kir1.x through Kir7.x) (Kubo et al., 2005 [1008]).

KCNJ10 (also known as KIR1.2; KIR4.1; SESAME; BIRK-10; KCNJ13-PEN) encodes Kir4.1, potassium inwardly-rectifying channel, subfamily J, member 10, characterized by having a greater tendency to allow potassium to flow into, rather than out of, a cell. The encoded protein may form a heterodimer with another potassium channel protein and may be responsible for the potassium buffering action of glial cells in the brain. Mutations in this gene have been associated with seizure susceptibility of common idiopathic generalized epilepsy syndromes.

http://www.ncbi.nlm.nih.gov/gene/3766


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Gene

Species NCBI gene ID Chromosome Position
Human 3766 1 32693
Mouse 16513 1 32875
Rat 29718 13 33357

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Transcript

Species NCBI accession Length (nt)
Human NM_002241.5 5205
Mouse NM_001039484.1 5407
Rat NM_031602.2 1438

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Protein Isoforms

Species Uniprot ID Length (aa)
Human P78508 379
Mouse Q9JM63 379
Rat P49655 379

Isoforms

Transcript
Length (nt)
Protein
Length (aa)
Variant
Isoform

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Post-Translational Modifications

PTM
Position
Type

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Structure

Kir4.1 predicted AlphaFold size

Species Area (Å2) Reference
Human 3505.22 source
Mouse 3569.08 source
Rat 4480.27 source

Methodology for AlphaFold size prediction and disclaimer are available here


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Expression and Distribution

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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CNS Sub-cellular 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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Function

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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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]).


References

202

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).

Ishii M 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).

Tanemoto M 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).

Higashi K et al. An inwardly rectifying K(+) channel, Kir4.1, expressed in astrocytes surrounds synapses and blood vessels in brain.
Am. J. Physiol., Cell Physiol., 2001 Sep , 281 (C922-31).

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).

Konstas AA 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).

Wu J et al. Expression and coexpression of CO2-sensitive Kir channels in brainstem neurons of rats.
J. Membr. Biol., 2004 Feb 1 , 197 (179-91).

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

To cite this page: [Contributors] Channelpedia https://channelpedia.epfl.ch/wikipages/50/ , accessed on 2024 Dec 02



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