phosphatidylcholine:ceramide cholinephosphotransferase 2; sphingomyelin synthase 2 (SGMS2, SMS2)

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
• required for cell growth
• palmitoylated on Cys-331, Cys-332, Cys-343 & Cys-348
  • palmitoylated plays a role in plasma membrane localization

ceramide + phosphatidylcholine = sphingomyelin + 1,2-diacyl-sn-glycerol

Inhibition:

• inhibited by bacterial PC-phospholipase C inhibitor D609

Structure

belongs to the sphingomyelin synthase family

Compartment

• plasma membrane, Golgi membrane
• predominantly plasma membrane, some in Golgi
• multi-pass membrane protein

Expression

• expressed brain, heart, kidney, liver, muscle & stomach

Notes

• overexpression of the human protein in mouse causes increased non-HDL-sphingomyelin & non-HDL cholesterol levels, decreased HDL-sphingomyelin & HDL-cholesterol levels & increases lipoprotein atherogenic potential

More general terms

• sphingomyelin synthase
• transmembrane 6 protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=166929
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:166929
• OMIM: https://mirror.omim.org/entry/611574
• UniProt: http://www.uniprot.org/uniprot/Q8NHU3.html