Kir4.2
Description: potassium inwardly-rectifying channel, subfamily J, member 15 Gene: Kcnj15 Alias: Kir4.2, kcnj15, irkk
KCNJ15 (also known as IRKK; KIR1.3; KIR4.2; MGC13584) encodes Kir4.2, an integral membrane protein, potassium inwardly-rectifying channel, subfamily J, member 15. The encoded protein has a greater tendency to allow potassium to flow into a cell rather than out of a cell. Three transcript variants encoding the same protein have been found for this gene.
http://www.ncbi.nlm.nih.gov/gene/3772
Experimental data
Rat Kir4.2 gene in CHO host cells |
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Gene
Transcript
| Species | NCBI accession | Length (nt) | |
|---|---|---|---|
| Human | NM_170736.3 | 8407 | |
| Mouse | NM_001039057.2 | 5138 | |
| Rat | NM_133321.2 | 1486 |
Protein Isoforms
Isoforms
Post-Translational Modifications
The residues involved in pHi sensing in Kir channels, such as the Inner Helix acidic residues (Xu [1035] and the ‘RKR triad’ (Schulte [1036], are identical in Kir4.1 and Kir4.2. (Lam [206]
Kir4.2 predicted AlphaFold size
Methodology for AlphaFold size prediction and disclaimer are available here
mKir4.2 expressed in Xenopus oocytes displayed a large inwardly rectifying K+ current with inward rectification being intermediate between that of the strong inward rectifier Kir2.1 and the weak inward rectifier Kir1.1. (Pearson [205])
Kir4.2 channels are expressed in a variety of transporting epithelial within the kidney (Gosset [1028], Lourdel [1029], Shuck [1030], Tucker [1021]), liver (Hill [1031], Glowatzki [1032]), pancreas (Pessias [3]), bladder, stomach and lung (Thiery [1033], and an airway mucosal cell line (Wu [1034]).
Kir4.2 current in Xenopus oocytes can be blocked by Ba+ and Cs+ and weakly blocked by TEA in a voltage-dependent fashion. Intracellular acidification decreased mKir4.2 current in a reversible fashion, while activation of protein kinase C decreased mKir4.2 current in a manner that was not rapidly reversible. Incubation of oocytes in elevated [K+] produced a slowly developing enhancement of current.(Pearson [205])
Kir4.2 can form functional homotetramers, or heterotetramers with Kir5.1. (Pearson [205]) Kir5.1 converts Kir4.2 from a strong to a weak rectifier, rendering it sensitive to pHi, and suggesting that Kir5.1 plays a role in fine-tuning Kir4.2 activity. (Lam [206])
References
Pearson WL
et al.
Expression of a functional Kir4 family inward rectifier K+ channel from a gene cloned from mouse liver.
J. Physiol. (Lond.),
1999
Feb
1
, 514 ( Pt 3) (639-53).
Lam HD
et al.
Modulation of Kir4.2 rectification properties and pHi-sensitive run-down by association with Kir5.1.
Biochim. Biophys. Acta,
2006
Nov
, 1758 (1837-45).
Pessia M
et al.
Differential pH sensitivity of Kir4.1 and Kir4.2 potassium channels and their modulation by heteropolymerisation with Kir5.1.
J. Physiol. (Lond.),
2001
Apr
15
, 532 (359-67).
Tucker SJ
et al.
pH dependence of the inwardly rectifying potassium channel, Kir5.1, and localization in renal tubular epithelia.
J. Biol. Chem.,
2000
Jun
2
, 275 (16404-7).
Gosset P
et al.
A new inward rectifier potassium channel gene (KCNJ15) localized on chromosome 21 in the Down syndrome chromosome region 1 (DCR1).
Genomics,
1997
Sep
1
, 44 (237-41).
Lourdel S
et al.
An inward rectifier K(+) channel at the basolateral membrane of the mouse distal convoluted tubule: similarities with Kir4-Kir5.1 heteromeric channels.
J. Physiol. (Lond.),
2002
Jan
15
, 538 (391-404).
Shuck ME
et al.
Cloning and characterization of two K+ inward rectifier (Kir) 1.1 potassium channel homologs from human kidney (Kir1.2 and Kir1.3).
J. Biol. Chem.,
1997
Jan
3
, 272 (586-93).
Hill CE
et al.
Cloning, expression, and localization of a rat hepatocyte inwardly rectifying potassium channel.
Am. J. Physiol. Gastrointest. Liver Physiol.,
2002
Feb
, 282 (G233-40).
Glowatzki E
et al.
Subunit-dependent assembly of inward-rectifier K+ channels.
Proc. Biol. Sci.,
1995
Aug
22
, 261 (251-61).
Thiery E
et al.
Developmentally regulated expression of the murine ortholog of the potassium channel KIR4.2 (KCNJ15).
Mech. Dev.,
2000
Jul
, 95 (313-6).
Wu JV
et al.
An inwardly rectifying potassium channel in apical membrane of Calu-3 cells.
J. Biol. Chem.,
2004
Nov
5
, 279 (46558-65).
Xu H
et al.
A single residue contributes to the difference between Kir4.1 and Kir1.1 channels in pH sensitivity, rectification and single channel conductance.
J. Physiol. (Lond.),
2000
Oct
15
, 528 Pt 2 (267-77).
Schulte U
et al.
pH gating of ROMK (K(ir)1.1) channels: control by an Arg-Lys-Arg triad disrupted in antenatal Bartter syndrome.
Proc. Natl. Acad. Sci. U.S.A.,
1999
Dec
21
, 96 (15298-303).
Credits
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