Spinophilin regulates Ca2+ signalling by binding the N-terminal domain of RGS2 and the third intracellular loop of G-protein-coupled receptors

Xinhua Wang, Weizhong Zeng, Abigail A. Syombo, Wei Tang, Elliott M. Ross, Anthony P. Barnes, Sharon L. Milgram, Josef M. Penninger, Patrick B. Allen, Paul Greengard, Shmuel Muallem

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122 Scopus citations

Abstract

Signalling by G proteins is controlled by the regulator of G-protein signalling (RGS) proteins that accelerate the GTPase activity of Gα subunits and act in a G-protein-coupled receptor (GPCR)-specific manner. The conserved RGS domain accelerates the Gα subunit GTPase activity, whereas the variable amino-terminal domain participates in GPCR recognition. How receptor recognition is achieved is not known. Here, we show that the scaffold protein spinophilin (SPL), which binds the third intracellualar loop (3iL) of several GPCRs, binds the N-terminal domain of RGS2. SPL also binds RGS1, RGS4, RGS16 and GAIP. When expressed in Xenopus laevis oocytes, SPL markedly increased inhibition of α-adrenergic receptor (αAR) Ca2+ signalling by RGS2. Notably, the constitutively active mutant αARA293E (the mutation being in the 3iL) did not bind SPL and was relatively resistant to inhibition by RGS2. Use of βAR-αAR chimaeras identified the 288REKKAA293 sequence as essential for the binding of SPL and inhibition of Ca2+ signalling by RGS2. Furthermore, αAR-evoked Ca2+ signalling is less sensitive to inhibition by SPL in rgs2-/- cells and less sensitive to inhibition by RGS2 in spl-/- cells. These findings provide a general mechanism by which RGS proteins recognize GPCRs to confer signalling specificity.

Original languageEnglish (US)
Pages (from-to)405-411
Number of pages7
JournalNature Cell Biology
Volume7
Issue number4
DOIs
StatePublished - Apr 1 2005

ASJC Scopus subject areas

  • Cell Biology

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    Wang, X., Zeng, W., Syombo, A. A., Tang, W., Ross, E. M., Barnes, A. P., Milgram, S. L., Penninger, J. M., Allen, P. B., Greengard, P., & Muallem, S. (2005). Spinophilin regulates Ca2+ signalling by binding the N-terminal domain of RGS2 and the third intracellular loop of G-protein-coupled receptors. Nature Cell Biology, 7(4), 405-411. https://doi.org/10.1038/ncb1237