sphingomyelin phosphodiesterase; acid sphingomyelinase; sphingomyelinase-1; asmase (SMPD1, ASM)

Function

• cleaves phosphatidylcholine from sphingomyelin
• converts sphingomyelin to ceramide
• also has phospholipase C activities toward
  • 1,2-diacylglycerolphosphocholine
  • 1,2-diacylglycerolphosphoglycerol
• isoforms 2 & 3 have lost catalytic activity

sphingomyelin + H2O = N-acylsphingosine + choline phosphate

Structure

• monomer
• belongs to the acid sphingomyelinase family
• contains 1 saposin B-type domain

Compartment

lysosome

Alternative splicing

named isoforms=3

Pathology

• deficient in Niemann-Pick disease, both
  • Niemann-Pick disease type A
  • Niemann-Pick disease type B

Polymorphism

• a common polymorphism arises from a variable number of hexanucleotide repeat sequence within the signal peptide region

Laboratory

• acid sphingomyelinase in leukocytes
• acid sphingomyelinase in dried blood spot

More general terms

• sphingomyelinase, sphinogomyelin phosphodiesterase

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=6609
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:6609
• OMIM: https://mirror.omim.org/entry/257200
• OMIM: https://mirror.omim.org/entry/607608
• OMIM: https://mirror.omim.org/entry/607616
• UniProt: http://www.uniprot.org/uniprot/P17405.html