Bidirectional lipid cholinephosphotransferase capable of converting phosphatidylcholine (PC) and ceramide to sphingomyelin (SM) and diacylglycerol (DAG) and vice versa. Direction is dependent on the relative concentrations of DAG and ceramide as phosphocholine acceptors. Directly and specifically recognizes the choline head group on the substrate. Also requires two fatty chains on the choline-P donor molecule in order to be recognized efficiently as a substrate. Does not function strictly as a SM synthase. Required for cell growth.
Brain, heart, kidney, liver, muscle and stomach.
Belongs to the sphingomyelin synthase family.
Palmitoylated on Cys-331, Cys-332, Cys-343 and Cys-348; which plays an important role in plasma membrane localization.
Cell membrane. Golgi apparatus membrane. Predominantly plasma membrane, some in Golgi apparatus.