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Neuron 2002 Jan 03;331:87-99. doi: 10.1016/s0896-6273(01)00567-0.
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G(alpha)(i) controls the gating of the G protein-activated K(+) channel, GIRK.

Peleg S , Varon D , Ivanina T , Dessauer CW , Dascal N .

GIRK (Kir3) channels are activated by neurotransmitters coupled to G proteins, via a direct binding of G(beta)(gamma). The role of G(alpha) subunits in GIRK gating is elusive. Here we demonstrate that G(alpha)(i) is not only a donor of G(beta)(gamma) but also regulates GIRK gating. When overexpressed in Xenopus oocytes, GIRK channels show excessive basal activity and poor activation by agonist or G(beta)(gamma). Coexpression of G(alpha)(i3) or G(alpha)(i1) restores the correct gating parameters. G(alpha)(i) acts neither as a pure G(beta)(gamma) scavenger nor as an allosteric cofactor for G(beta)(gamma). It inhibits only the basal activity without interfering with G(beta)(gamma)-induced response. Thus, GIRK is regulated, in distinct ways, by both arms of the G protein. G(alpha)(i) probably acts in its GDP bound form, alone or as a part of G(alpha)(beta)(gamma) heterotrimer.

PubMed ID: 11779482
Article link: Neuron
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: kcnj3 kidins220

References :
Kovoor, Gi Irks GIRKs. 2002, Pubmed