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Kir3.4

potassium inwardly-rectifying channel, subfamily J, member 5
Synonyms: Kir3.4 Girk4 kcnj5. Symbol: Kcnj5

Introductions


Genes


Kcnj5 : potassium inwardly-rectifying channel, subfamily J, member 5

RGD ID Chromosome Position Species
61971 8 32082866-32104412 Rat
62264 9 32122368-32151822 Mouse
1349904 11 128761313-128787964 Human

Transcripts


Acc No Sequence Length Source
NM_017297 NCBI
NM_010605 NCBI
NM_000890 NCBI

Ontologies


Accession Name Definition Evidence
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
GO:0009897 external side of plasma membrane The side of the plasma membrane that is opposite to the side that faces the cytoplasm. IDA
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:0030315 T-tubule Invagination of the plasma membrane of a muscle cell that extends inward from the cell surface around each myofibril. The ends of T-tubules make contact with the sarcoplasmic reticulum membrane. IDA

Interactions


Co-expression of Kir2.1 with Kir3.4 in Xenopus oocytes and HEK293T cells did not yield currents with distinguishable features. However, co-expression of a dominant-negative Kir2.1 with the wild-type Kir3.4 decreased the Kir3.4 current amplitude in Xenopus oocytes. The results indicate that Kir2.1 is capable of forming heteromultimeric channels with Kir3.4. (Ishihara [996])

Stimulation of the M2 receptor by ACh causes dissociation of the coupled G-protein and the Gbc-subunits activate the Kir3.1/3.4 channel by direct binding (Logothetis [1002]).

phosphatidylinositol (4,5)-bisphosphate (PIP2) is a requirement for Kir channels activity and a decrease in bound PIP2 strongly decreases the open probability of the Kir3.1/ 3.4 channels (Huang [1003], Sui [1004]).

GIRK1/4 channel current can be blocked by BaCl(2) and enhanced by increasing the driving force for K(+) across the cell membrane. (Walsh [995])

Proteins


Structures


Distributions


Expressions


Kir3.1 is expressed in the heart and brain (Kubo [1000]), and is known to assemble with Kir3.4 in SAN and atrial myocytes in the heart and with Kir3.2 in the brain to form functional channels (Krapivinsky [998], Velimirovic [999]).

Functionals


Kir3.1 and Kir3.4, expressed mainly in SAN and atrial myocytes in the heart, form heterotetrameric channels, which are coupled to m2 muscarinic receptor via G-protein bc subunits and carry the ACh-activated K+ current (IK,ACh) regulating the heart rate (Krapivinsky [998], Corey [1001]).

Mice deficient of Kir3.1 or 3.4 exhibit mild resting tachycardia (Bettahi [1005]) and impaired beat-to-beat control (Wickman [1006]).

Kir3.4 deficient mice were resistant to atrial fibrillation caused by vagal stimulation (Kovoor [1007]). Kir3.4 could be predisposing to or even protecting against atrial fibrillation (Calloe [997]).

Kinetics


Models


References


[196 : 10341034]
[197 : 10092682]
[198 : 9409468]
[199 : 10998041]
[200 : 11159438]
[201 : 17960365]
[995 : 20938046]
[996 : 19338762]
[997 : 17967416]
[998 : 7877685]
[999 : 8566224]
[1000 : 8355805]
[1001 : 9478984]
[1002 : 2433589]
[1003 : 9486652]
[1004 : 8923264]
[1005 : 12374786]
[1006 : 9459446]
[1007 : 11419900]

Credits