A number of phosphatidyltransferases, which are all involved in phospholipidbiosynthesis and that share the property of catalyzing the displacement of CMPfrom a CDP-alcohol by a second alcohol with formation of a phosphodiester bondand concomitant breaking of a phosphoride anhydride bond share a conservedsequence region.These enzymes are proteins of 200 to 400 amino acid residues. Theconserved region contains three aspartic acid residues and is located in theN-terminal section of the sequences.