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Sci. Signal., 8 February 2011
Vol. 4, Issue 159, p. pe5
[DOI: 10.1126/scisignal.2001798]


G{alpha}q and Phospholipase C-β: Turn On, Turn Off, and Do It Fast

Elliott M. Ross*

Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390–9041, USA.

Abstract: Heterotrimeric G proteins and G protein–coupled receptors represent conserved protein families with origins in the prokaryotes, but the various G protein–regulated effectors are heterogeneous in structure and function. The effectors apparently evolved ways to listen to G proteins late in their evolutionary histories. The structure of a complex between the effector protein phospholipase C-β3 (PLC-β3) and its activator, G{alpha}q, suggests that several effectors independently evolved a structurally similar helix-turn-helix segment for G protein recognition. PLC-βs are also guanosine triphosphatase (GTPase)–activating proteins (GAPs) for the Gq that activates them. In a second example of convergent evolution, the GAP activity of these proteins depends on a flexible asparagine-containing loop that resembles the GAP site on RGS proteins, another family of G protein GAPs. Together, these two sites are proposed to cooperate to enable fast binding to activated G{alpha}q, followed by fast deactivation. This cycle allows rapid sampling of the activation state of Gq-coupled receptors while providing efficient signal transduction.

* Corresponding author. Telephone, 214-645-6134; e-mail, ross{at}

Citation: E. M. Ross, G{alpha}q and Phospholipase C-β: Turn On, Turn Off, and Do It Fast. Sci. Signal. 4, pe5 (2011).

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