G protein-coupled inwardly rectifying potassium channel

Source: Wikipedia, the free encyclopedia.
(Redirected from
G protein-coupled inwardly-rectifying potassium channel
)
Chr. 2 q24.1
Search for
StructuresSwiss-model
DomainsInterPro
Chr. 21 q22.1
Search for
StructuresSwiss-model
DomainsInterPro
Chr. 1 q23.2
Search for
StructuresSwiss-model
DomainsInterPro
Chr. 11 q24
Search for
StructuresSwiss-model
DomainsInterPro

The G protein-coupled inwardly rectifying potassium channels (GIRKs) are a family of

Gβγ) from inactive heterotrimeric G protein complexes (Gαβγ). Finally, the Gβγ dimeric protein interacts with GIRK channels to open them so that they become permeable to potassium ions, resulting in hyperpolarization of the cell membrane.[3] G protein-coupled inwardly rectifying potassium channels are a type of G protein-gated ion channels
because of this direct interaction of G protein subunits with GIRK channels. The activation likely works by increasing the affinity of the channel for PIP2. In high concentration PIP2 activates the channel absent G-protein, but G-protein does not activate the channel absent PIP2.

GIRK1 to GIRK3 are distributed broadly in the central nervous system, where their distributions overlap.[4][5][6] GIRK4, instead, is found primarily in the heart.[7]

Subtypes

protein gene aliases
GIRK1 KCNJ3 Kir3.1
GIRK2 KCNJ6 Kir3.2
GIRK3 KCNJ9 Kir3.3
GIRK4 KCNJ5 Kir3.4

Examples

A wide variety of G protein-coupled receptors activate GIRKs, including the

CB2, and sphingosine-1-phosphate receptors.[2][3][8]

Examples of GIRKs include a subset of potassium channels in the heart, which, when activated by

M2 muscarinic receptors, causes an outward current of potassium, which slows down the heart rate.[9][10] These are called muscarinic potassium channels (IKACh) and are heterotetramers composed of two GIRK1 and two GIRK4 subunits.[7][11]

References

  1. PMID 9429760
    .
  2. ^
    PMID 9860808
    .
  3. ^
    PMID 21772817
    . inhibition of firing due to increased release of dopamine; (b) reduction of D2 and GABAB receptor-mediated inhibitory responses (excitatory effects due to disinhibition); and (c) a direct TA1 receptor-mediated activation of GIRK channels which produce cell membrane hyperpolarization.
  4. PMID 7702616
    .
  5. PMID 8642402
    .
  6. S2CID 13599513
    .
  7. ^
    S2CID 4334467
    .
  8. S2CID 4851569
    .
  9. S2CID 14720432
    .
  10. S2CID 25949938. Archived from the original
    on 2006-01-29. Retrieved 2008-02-03.
  11. PMID 9478984
    .

External links