Purification of ethanolaminephosphotransferase from bovine liver microsomes

CDP-ethanolamine :diacylglycerol ethanolaminephosphotransferase (EC 2.7.8.1 ) has been purified to electrophoretic homogeneity and in a catalytically a ctive form from bovine liver microsomes. The purification method is based o n the high hydrophobicity of the protein whose charged sites appear to be m asked from the interaction with the chromatographic stationary phases when membranes are solubilized with an excess of non-ionic detergent. The isolated protein has a molecular mass of about 38 kDa, as estimated by SDS-PAGE mobility, and exhibits both ethanolaminephosphotransferase and cho linephosphotransferase activities. Evidence is given that both activities a re Mn2+-dependent and that the same catalytic site is involved in cholineph osphotransferase and ethanolaminephosphotransferase reactions. Mg2+-depende nt CDP-choline :diacylglycerol cholinephosphotransferase (EC 2.7.8.2) is co mpletely inactivated during the solubilization and purification steps. (C) 1999 Elsevier Science B.V. All rights reserved.