phosphatidylcholine:ceramide cholinephosphotransferase 1; medulla oblongata-derived protein; protein Mob; sphingomyelin synthase 1; transmembrane protein 23 (SGMS1, MOB, SMS1, TMEM23)

Function: - bidirectional lipid cholinephosphotransferase capable of converting phosphatidylcholine & ceramide to sphingomyelin & diacylglycerol & vice versa - direction is dependent on the relative concentrations of diacylglycerol & ceramide as phosphocholine acceptors - directly & 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 sphingomyelin synthase - suppresses BAX-mediated apoptosis - prevents cell death in response to stimuli such as hydrogen peroxide, osmotic stress, elevated temperature & exogenously supplied sphingolipids - may protect against cell death by reversing the stress-inducible increase in levels of proapoptotic ceramide - required for cell growth ceramide + phosphatidylcholine = sphingomyelin + 1,2-diacyl-sn-glycerol Inhibition: - inhibited by bacterial PC-phospholipase C inhibitor D609 Structure: - belongs to the sphingomyelin synthase family - contains 1 SAM (sterile alpha motif) domain Compartment: - Golgi membrane - multi-pass membrane protein Alternative splicing: named isoforms=2 Expression: brain, heart, kidney, liver, muscle and stomach Miscellaneous: overexpression of the human protein in mouse causes increased non-HDL-sphingomyelin & non-HDL cholesterol levels, decreased HDL-sphingomyelin & HDL-cholesterol levels and increases lipoprotein atherogenic potential

General

sphingomyelin synthase (phosphatidylcholine:ceramide cholinephosphotransferase) transmembrane 5 protein

Properties

SIZE: entity length = 419 aa MW = 49 kD COMPARTMENT: golgi MOTIF: exoplasmic domain {1-141} MOTIF: sterile alpha motif NAME: sterile alpha motif SITE: 13-76 transmembrane domain {142-162} cytoplasmic loop {164-189} transmembrane domain {190-210} exoplasmic loop {211-220} transmembrane domain {221-241} cytoplasmic loop {242-281} transmembrane domain {282-302} EXOOPLASMIC-LOOP :SITE RANGE :LOW 303 :HIGH 309 transmembrane domain {310-330} cytoplasmic domain {331-419}

Database Correlations

OMIM 611573 UniProt Q86VZ5 PFAM correlations Entrez Gene 259230 Kegg hsa:259230 ENZYME 2.7.8.27

References

UniProt :accession Q86VZ5