Phosphatidylcholine:ceramide cholinephosphotransferase 1 (EC 2.7.8.27) (Medulla oblongata-derived protein) (Protein Mob) (Sphingomyelin synthase 1) (Transmembrane protein 23)
1_MKEVV 6_ YWSPK 11_ KVADW 16_ LLENA 21_ MPEYC 26_ EPLEH 31_ FTGQD 36_ LINLT 41_ QEDFK 46_ KPPLC 51_ RVSSD 56_ NGQRL 61_ LDMIE 66_ TLKME 71_ HHLEA 76_ HKNGH 81_ ANGHL 86_ NIGVD 91_ IPTPD 96_ GSFSI 101_ KIKPN 106_ GMPNG 111_ YRKEM 116_ IKIPM 121_ PELER 126_ SQYPM 131_ EWGKT 136_ FLAFL 141_ YALSC 146_ FVLTT 151_ VMISV 156_ VHERV 161_ PPKEV 166_ QPPLP 171_ DTFFD 176_ HFNRV 181_ QWAFS 186_ ICEIN 191_ GMILV 196_ GLWLI 201_ QWLLL 206_ KYKSI 211_ ISRRF 216_ FCIVG 221_ TLYLY 226_ RCITM 231_ YVTTL 236_ PVPGM 241_ HFNCS 246_ PKLFG 251_ DWEAQ 256_ LRRIM 261_ KLIAG 266_ GGLSI 271_ TGSHN 276_ MCGDY 281_ LYSGH 286_ TVMLT 291_ LTYLF 296_ IKEYS 301_ PRRLW 306_ WYHWI 311_ CWLLS 316_ VVGIF 321_ CILLA 326_ HDHYT 331_ VDVVV 336_ AYYIT 341_ TRLFW 346_ WYHTM 351_ ANQQV 356_ LKEAS 361_ QMNLL 366_ ARVWW 371_ YRPFQ 376_ YFEKN 381_ VQGIV 386_ PRSYH 391_ WPFPW 396_ PVVHL 401_ SRQVK 406_YSRLV
1: Major sphingomyelin synthase at the Golgi apparatus (PubMed:14685263, PubMed:17449912). Catalyzes the reversible transfer of phosphocholine moiety in sphingomyelin biosynthesis: in the forward reaction transfers phosphocholine head group of phosphatidylcholine (PC) on to ceramide (CER) to form ceramide phosphocholine (sphingomyelin, SM) and diacylglycerol (DAG) as by-product, and in the reverse reaction transfers phosphocholine from SM to DAG to form PC and CER. The direction of the reaction depends on the levels of CER and DAG in Golgi membranes (PubMed:14685263, PubMed:14976195, PubMed:17449912, PubMed:17982138, PubMed:19454763). Converts the newly synthesized CER, that is transported from the endoplasmic reticulum to the trans-Golgi by the Cer transport protein (CERT), to SM (PubMed:30242129). Can form a heteromeric complex with glucosylceramide synthase (GCS) increasing SMS activity and reducing glucosylceramide synthesis, a critical mechanism that controls the metabolic fate of CER in the Golgi (PubMed:30242129). Does not use free phosphorylcholine or CDP-choline as donor (PubMed:14685263, PubMed:14976195). Can also transfer phosphoethanolamine head group of phosphatidylethanolamine (PE) on to CER to form ceramide phosphoethanolamine (CPE) (By similarity). Regulates receptor-mediated signal transduction via mitogenic DAG and proapoptotic CER, as well as via SM, a structural component of membrane rafts that serve as platforms for signal transduction and protein sorting (PubMed:14976195, PubMed:17449912, PubMed:17982138). Plays a role in secretory transport via regulation of DAG pool at the Golgi apparatus and its downstream effects on PRKD1 (PubMed:18370930, PubMed:21980337)