Abstract
Approximately 40 % of Arabidopsis proteins are predicted to contain membrane-spanning domains, anchoring them to lipid bilayers as integral membrane proteins. In addition to the ion transporters facilitating transport of nutrients and metabolites across the membranes, proteins that may potentially regulate the ion transport systems in response to various environmental stresses can be included in this category. GeneChip analysis of sulfur-starved Arabidopsis plants indicated that several putative membrane-bound proteins as well as the isoforms of functional sulfate transporters accumulate during sulfur limitation. Membrane-bound proteins were selected by a plant membrane protein database, ARAMEMNON (http://aramemnon.botanik.uni-koeln.de./). In particular, we focused on the functions of proteins that stimulate the activity of sulfate transport in yeast-expression system. T-DNA knockouts and over-expressors of these primary candidates are analyzed for identification of their protein functions.
