What do we do? My lab is interested in signal transduction networks in plant cells, specifically, G-protein coupled pathways. The classical model for heterotrimeric G-protein coupling is shown in the figure. Briefly, G-protein coupled receptors have 7 transmembrane domains (brown lines in figure). The amino-terminal extension is extracellular and determines ligand specificity.
Ligand binding activates the associated G-protein complex by releasing activated Ga subunits (cyan in figure) and Gbg dimers (pink in figure) that target downstream effectors, typically enzymes (noted as E1 and E2 in the figure) that produce large amount of secondary messengers. The pathway turns itself off but this “powering down” can be accelerated by Regulators of G Signaling (RGS) proteins as shown (red starburst). The receptor causes the GDP bound to the Ga to exchange for GTP, thus you can think of this receptor as a guanine exchange factor (GEF). The RGS protein is a GTPase accelerating protein (GAP).
Why do we use Arabidopsis? Arabidopsis is a genetic model organism that has many similarities but also differences with mammalian cells? Arabidopsis uses G-coupled signaling but many features about it make it ideal as a model for G-protein signaling research. Unlike in humans where there are dozens or more genes encoding each component of the pathway shown in the figure, the Arabidopsis genome encodes a single canonical Gα, Gβ, and two Gγ subunits and only one RGS protein, ideal for genetically dissecting the role of the heterotrimeric G protein in cell responses.a
How do we do it? My lab takes forward and reverse genetic approaches to understand G protein coupled signaling in plant cells. We couple this with some specific biological context such as hormone or light induced growth and differentiation and include extensive biochemistry. We have shown that the single Arabidopsis G protein mediates plant cell proliferation. What we are focusing on now is what signals are coupled by this G protein and what are the receptors. We are interested in the structure that imparts the unique features of G signaling in Arabidopsis and applying these to signaling in mammals.
The details, job opportunities, and resources. For more information about G proteins in plants and to meet the people involved in this research, see my lab web page. There, also, you will find a database about plant G-protein signaling and some tools for G-protein research.