Two chimeric regulators of G-protein signaling (RGS) proteins differentially modulate soybean heterotrimeric G-protein cycle.

ABSTRACT: Heterotrimeric G-proteins and the regulator of G-protein signaling (RGS) proteins, which accelerate the inherent GTPase activity of G? proteins, are common in animals and encoded by large gene families; however, in plants G-protein signaling is thought to be more limited in scope. For example, Arabidopsis thaliana contains one G?, one G?, three G?, and one RGS protein. Recent examination of the Glycine max (soybean) genome reveals a larger set of G-protein-related genes and raises the possibility of more intricate G-protein networks than previously observed in plants. Stopped-flow analysis of GTP-binding and GDP/GTP exchange for the four soybean G? proteins (GmG?1-4) reveals differences in their kinetic properties. The soybean genome encodes two chimeric RGS proteins with an N-terminal seven transmembrane domain and a C-terminal RGS box. Both GmRGS interact with each of the four GmG? and regulate their GTPase activity. The GTPase-accelerating activities of GmRGS1 and -2 differ for each GmG?, suggesting more than one possible rate of the G-protein cycle initiated by each of the G? proteins. The differential effects of GmRGS1 and GmRGS2 on GmG?1-4 result from a single valine versus alanine difference. The emerging picture suggests complex regulation of the G-protein cycle in soybean and in other plants with expanded G-protein networks.

SUBMITTER: Choudhury SR 

PROVIDER: S-EPMC3366798 | biostudies-other | 2012 May

REPOSITORIES: biostudies-other