Primary sodium plasma membrane ATPases in salt-tolerant algae: facts and fictions.
For thermodynamic reasons algae growing in media of both high salinity and high alkalinity require active export of sodium. However, experimental evidence for an active Na+-dependent cycle was scarce until recently, in contrast to the situation in marine bacteria (including cyanobacteria), fungi and animals. However, a review of literature reveals that some progress has been made in this respect, recently: data demonstrate that at least in two marine algae, Tetraselmis (Platymonas) viridis and Heterosigma akashiwo (syn. Olisthodiscus luteus), active Na+-export is carried out by means of a plasma membrane localized Na+-pump (apparent molecular mass 100-140 kDa). Biochemical characteristics of this vanadate-sensitive, but ouabain-resistant primary P-type Na+-ATPase are described and compared with the corresponding properties of Na+-ATPase from prokaryotes and animals. Alternative mechanisms for Na+-pumping are discussed.
Julius-von-Sachs Institute of Bioscience, University of Würzburg, Germany. gimmler@botanik.uni-wuerzburg.de
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D000255:Adenosine Triphosphate / Q000378:metabolism*; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000378:metabolism; D056890:Eukaryota / Q000201:enzymology / Q000378:metabolism*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012623:Seawater; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism
D008565:Membrane Proteins; D000255:Adenosine Triphosphate; D000254:Sodium-Potassium-Exchanging ATPase