Reactome | G-protein activation

G-protein activation

Stable Identifier

R-HSA-202040

Type

Pathway

Species

Homo sapiens

ReviewStatus

5/5

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Receptor activated heterotrimeric G proteins consist of the Galpha and the tightly associated Gbeta-gamma subunits. When a ligand binds to a G protein-coupled receptor, it stabilises a conformation with an high affinity for the G-protein bound to GDP. GDP is then exchanged for GTP on the Galpha subunit. This exchange triggers the dissociation of the Galpha subunit from the Gbeta-gamma dimer and the receptor. Galpha-GTP and Gbeta-gamma, can then modulate different signalling cascades and effector proteins, while the receptor is able to activate another G protein, resulting in an amplification cascade. The Galpha subunit will eventually hydrolyze the attached GTP to GDP by its inherent enzymatic activity, allowing it to reassociate with Gbeta-gamma and start a new cycle.

Literature References

PubMed ID	Title	Journal	Year
9218123	G proteins and opioid receptor-mediated signalling Pasternak, GW, Standifer, KM	Cell Signal	1997
12184727	Differential mechanism of G-protein activation induced by endogenous mu-opioid peptides, endomorphin and beta-endorphin Sora, I, Suzuki, T, Mizoguchi, H, Narita, M, Tseng, LF	Jpn J Pharmacol	2002
15294442	G protein activation by G protein coupled receptors: ternary complex formation or catalyzed reaction? Waelbroeck, M, Roberts, DJ	Biochem Pharmacol	2004