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.
