>A post-doctoral position is available for a molecular biologist interested
in functional analysis of plant G-proteins (see description below).
Candidates should ideally have experience with plant transformation, yeast
two-hybrid analysis, screening for T-DNA tagged mutants, and/or biochemical
analysis of GTP-binding proteins. The position is initially available for
two years; salary is commensurate with experience. If interested, please
send a cover letter detailing research experience and interests, a c.v., and
names, e-mail addresses, and phone numbers of three individuals willing to
provide letters of reference to:
>>Dr. Sally Assmann
>Penn State University
>208 Mueller Laboratory
>University Park, PA
>>Tel. (814) 863-9579
>FAX (814) 865-9131
>e-mail: sma3 at psu.edu>>Heterotrimeric GTP-binding proteins, composed of alpha, beta, and gamma
subunits, are involved in signal transduction pathways in animal and plant
systems. In plants, physiological analyses implicate heterotrimeric
G-proteins in ion channel regulation (see references below), light
signaling, and hormone and pathogen responses. However, only one class of
plant Galpha genes has been characterized to date. We have cloned a novel
gene, "Arabidopsis thaliana extra-large GTP-binding protein" (AtXLG1). The
conceptually translated protein from AtXLG1 is 99 kDa, twice as large as
typical Galpha proteins. The carboxy-terminal half of the AtXLG1 protein has
significant homology to animal and plant Galpha proteins, and recombinant
AtXLG1 binds GTP with specificity. The amino-terminal region of AtXLG1
contains domains homologous to the bacterial TonB-box, which is involved in
energy transduction between the inner and outer bacterial membranes, and to
zinc-finger proteins. Molecular genetic and biochemical approaches will be
used to uncover the physiological functions of this novel GTP-binding protein.
Fairley-Grenot, K.A., Assmann, S.M. (1991) Evidence for G-protein regulation
of inward K+ channel current in
guard cells of fava bean. Plant Cell 3: 1037-1044.
Li, W., Assmann, S.M. (1993) Characterization of a G-protein regulated
outward K+ current in mesophyll cells
of Vicia faba L. PNAS 90: 262-266.
Wu, W, Assmann, S.M. (1994) A membrane-delimited pathway of G-protein
regulation of the guard cell inward K+ channel. PNAS 91: 6310-6314.
Assmann, S.M. (1996) G-protein regulation of plant K+ channels. in D.P.S.
Verma, ed. Signal Transduction in
Plant Growth and Development. Springer, NY pp39-61.