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.