A purified alanine carrier composed of a single polypeptide from thermophilic bacterium PS3 driven by either proton or sodium ion gradient.

An alanine carrier protein was isolated from membranes of the thermophilic bacterium PS3 using ion exchange column chromatography followed by high performance liquid chromatography with a hydroxylapatite column. The final preparation consisted of a single polypeptide, with Mr = 42,500, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A polarity index of 33% was calculated from the amino acid analysis. Proteoliposomes reconstituted with the purified alanine carrier carried out an active alanine transport driven by either an electrochemical potential difference of protons or that of sodium ions.