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Kir4.1

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

Introductions


Genes


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

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

Transcripts


Acc No Sequence Length Source
NM_031602 NCBI
NM_001039484 NCBI
NM_002241 NCBI

Ontologies


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

Interactions


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]).

Proteins


Structures


Distributions


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]).

Expressions


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]).

Functionals


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]).

Kinetics


Models


References


[202 : 17071817]
[203 : 17585871]
[204 : 11927671]
[1008 : 16382105]
[1009 : 7608203]
[1010 : 12686518]
[1011 : 10797616]
[1012 : 15310750]
[1013 : 10856114]
[1014 : 11502569]
[1015 : 10088671]
[1016 : 12578959]
[1017 : 16257493]
[1018 : 12923169]
[1019 : 12456399]
[1020 : 11306656]
[1021 : 10764726]
[1022 : 10790154]
[1023 : 10871638]
[1024 : 11598908]
[1025 : 11738651]
[1026 : 15042349]
[1027 : 15292049]

Credits