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Post-doctoral position in Membrane biology

hs29 Heven_SZE at umail.umd.edu
Tue Aug 25 10:58:22 EST 1998

Post-doctoral Position in Membrane Biology

Available Fall/Winter 1998
University of Maryland, College Park

A postdoctoral position is available to study one of several ongoing
projects on proton and calcium pumps in plants.  One is to understand the
biosynthesis and assembly of the vacuolar H+-pumping ATPase (The Plant Cell
10, 119 [1998]), and to determine the roles of multiple V-ATPases expressed
in Arabidopsis thaliana (Plant Mol Biol. 29: 227 [1995]).  Another project
is to understand the regulation of two distinct types of plant Ca-pumping
ATPases that have been functionally expressed in yeast (Proc Natl Acad Sci
94, 8579 [1997]; J Biol Chem 273, 1099 [1998]).  Recent graduates with
interest and experience in cell biology, biochemistry and molecular biology
are preferred.  Send a statement of professional interests and goals,
summary of previous experience, curriculum vitae and letters from two
referees to:

Dr. Heven Sze
Dept. Cell Biology and Molecular Genetics
HJ Patterson Hall
University of Maryland
College Park, MD 20742-5815
email: hs29 at umail.umd.edu


        The role of Ca as an intracellular signal and as a player in the
secretory system necessitates regulation of the cytosolic and endolumenal
ion activity in plant cells.  When cytosolic [Ca] increases due to various
stimuli, Ca pumps at the plasma membrane and on organelles are activated to
restore [Ca] to basal levels.  Endolumenal [Ca] supplied by Ca pumps is also
important for the normal operation of the secretory system.  Thus multiple
Ca-ATPases may differ in their structure, membrane location and function in
order to regulate localized [Ca].  In spite of the multiplicity of Ca pumps
in plants, the properties, membrane location and expression of each
individual pump are not well understood.  To study individual pumps from
Arabidopsis thaliana, we have expressed two types of Ca-ATPase genes that
complement a yeast mutant defective in Ca pumps.  ECA1 encodes an ER-type
Ca-ATPase that is insensitive to calmodulin; whereas ACA2 encodes another
Arabidopsis Ca-ATPase that is regulated by an N-terminal domain.  The
central goal of  this proposal is to characterize the biochemical properties
of each pump and to begin defining the functional and regulatory domains by
molecular dissection.  Specifically, we propose to (i) determine the
transport properties of ECA1p expressed in yeast, and the subcellular
location in A. thaliana plants; (ii) determine the Ca transport properties
of ACA2p, and define the residues and specific domains necessary for
regulatory functions at the N-terminal region; (iii) determine the
regulation of an ER Ca pump (ECA1) activity; (iv) identify additional Ca
pump genes in A. thaliana to determine their function and membrane location,
and (v) if time permits, study the fate of ECA1p-tagged with the green
fluorescent protein in dynamic living cells.  The ability to express
individual plant Ca pump genes functionally in yeast is a major step towards
defining the function and regulation of each Ca pump, and understanding how
plants respond to hormonal and environmental signals during their growth and

Heven SZE
Department of Cell Biology & Molecular Genetics
HJ Patterson Hall Rm 3232
University of Maryland
College Park, MD 20742-5815

Email:Heven_SZE at umail.umd.edu (hs29)
Phone:(301) 405-1645
Fax: (301) 314-9082

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