Bidirectional lipid cholinephosphotransferase capable of converting inositol phosphorylceramide (IPC) 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. Essential for viability of the pathogenic bloodstream stage of this human protozoan parasite and, consequently, can be considered as potential drug target. a 1,2-diacyl-sn-glycero-3-phosphocholine + an N-acylsphing-4-enine = a 1,2-diacyl-sn-glycerol + a sphingomyelin Expressed in both bloodstream and procyclic stage parasites. Elevated ceramide levels and growth arrest; cells were arrested in division but replication of DNA and organelles continued giving rise to cells containing multiple nuclei, kinetoplasts and flagella. Belongs to the sphingomyelin synthase family.