Poster: Signaling, cell-to-cell

Abs # 425: Role of a Seven-transmembrane RGS Protein in Sugar Signaling in Arabidopsis

Presenter:	Jones, Alan M., alan_jones@unc.edu
Authors	Jones, Alan M. (A)   Chen, Jin-Gui  (A)   Huang, Jirong  (A)
Affiliations:	(A): Dept. of Biology, University of North Carolina at Chapel Hill

Regulators of G Signaling (RGS) proteins accelerate the intrinsic GTPase activity of the alpha subunit of heterotrimeric G proteins and thereby desensitize cells to signals that are coupled by G proteins. Arabidopsis contains a single RGS1 protein. This RGS (AtRGS1) contains a seven-transmembrane domain at its amino-terminal half and a functional RGS domain at its cytosolic-facing, C-terminal half. D-glucose serves as both a metabolite and a hormone-like signal that regulates plant cell proliferation. High D-glucose arrests cell proliferation, but Arabidopsis mutants lacking AtRGS1 are insensitive to high concentrations of D-glucose. Conversely, plants ectopically expressing AtRGS1 are hypersensitive to sugars. D-glucose, but not L-glucose, causes rapid internalization of a AtRGS1:GFP fusion protein. These results raise the possibility that AtRGS1 is a glucose receptor that controls cell proliferation through regulation of the active state of its cognate G-protein complex.