title: Functional expression and cellular localization of the Na+/H+ exchanger Sod2 of the fission yeast Schizosaccharomyces pombe.
abstract: In the fission yeast Schizosaccharomyces pombe, the Na+/H+ exchanger, Sod2, plays a major role in the removal of excess intracellular sodium, and its disruption results in a sodium-sensitive phenotype. We examined the subcellular distribution and dynamics of Sod2 expression in S. pombe using a sod2-GFP fusion protein under the control of an attenuated version of the inducible nmt promoter. Sod2 was localized throughout the plasma membrane, the nuclear envelope, and some internal membrane systems. In exponentially growing cells, in which sod2-GFP was expressed and then the promoter turned-off, previously synthesized sod2-GFP was stable for long periods and found localized to the plasma membrane in the medial regions of the cell. It was not present at the actively growing cell ends. This suggests that these regions of the cell contain old plasma membrane protein vs. newly synthesized plasma membrane without Sod2 at the growing ends. Sod2 localization was not affected by salt stress. The results suggest that Sod2 is both a plasma membrane protein and is present in intracellular membranes. It is likely tethered within discrete regions of the plasma membrane and is not free to diffuse throughout the bilayer.
authors.affiliation: Department of Biochemistry, 347 Medical Science Building, University of Alberta, Edmonton, Alberta T6G 2H7, Canada. lfliegel@ualberta.ca
authors.forename: Larry
authors.initials: L
authors.lastname: Fliegel
authors.forename: Christine
authors.initials: C
authors.lastname: Wiebe
authors.forename: Gordon
authors.initials: G
authors.lastname: Chua
authors.forename: Paul G
authors.initials: PG
authors.lastname: Young
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D003470:Culture Media; D049452:Green Fluorescent Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012568:Schizosaccharomyces / Q000378:metabolism* / Q000648:ultrastructure; D029702:Schizosaccharomyces pombe Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: D003470:Culture Media; D008565:Membrane Proteins; D029702:Schizosaccharomyces pombe Proteins; C501077:Sod2 protein, S pombe; D017923:Sodium-Hydrogen Exchangers; D049452:Green Fluorescent Proteins