G-protein activation

Stable Identifier
Homo sapiens
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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
Orthologous Events
Cross References
BioModels Database
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