Source:http://www.reactome.org/biopax/48887BiochemicalReaction3501
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Authored: Jupe, S, 2009-02-27 15:59:25,
Edited: Jupe, S, 2009-09-09,
Reviewed: Akkerman, JW, 2009-06-03,
When a ligand activates a G protein-coupled receptor, it induces a conformational change in the receptor (a change in shape) that allows the receptor to function as a guanine nucleotide exchange factor (GEF), stimulating the exchange of GDP for GTP on the G alpha subunit. In the traditional view of heterotrimeric protein activation, this exchange triggers the dissociation of the now active G alpha subunit from the beta:gamma dimer, initiating downstream signalling events. The G alpha subunit has intrinsic GTPase activity and will eventually hydrolyze the attached GTP to GDP, allowing reassociation with G beta:gamma. Additional GTPase-activating proteins (GAPs) stimulate the GTPase activity of G alpha, leading to more rapid termination of the transduced signal. In some cases the downstream effector may have GAP activity, helping to deactivate the pathway. This is the case for phospholipase C beta, which possesses GAP activity within its C-terminal region.
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G alpha (i) auto-inactivates by hydrolysing GTP to GDP
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3.6.5.1,
3.6.5.2,
3.6.5.3,
3.6.5.4
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