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sphingomyelin phosphodiesterase; acid sphingomyelinase; sphingomyelinase-1; asmase (SMPD1, ASM)
Function:
- cleaves phosphatidylcholine from sphingomyelin
- converts sphingomyelin to ceramide
- also has phospholipase C activities toward
a) 1,2-diacylglycerolphosphocholine
b) 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
Polymorphism:
- a common polymorphism arises from a variable number of hexanucleotide repeat sequence within the signal peptide region
Pathology:
- deficient in Niemann-Pick disease, both
a) Niemann-Pick disease type A
b) Niemann-Pick disease type B
Laboratory:
- acid sphingomyelinase in leukocytes
- acid sphingomyelinase in dried blood spot
General
sphingomyelinase, sphinogomyelin phosphodiesterase
Properties
SIZE: entity length = 629 aa
MW = 70 kD
COMPARTMENT: lysosome
MOTIF: signal sequence {1-46}
Saposin B-type {85-169}
MOTIF: N-glycosylation site {N86}
cysteine residue {C89}
MODIFICATION: cysteine residue {C165}
cysteine residue {C92}
MODIFICATION: cysteine residue {C157}
cysteine residue {C120}
MODIFICATION: cysteine residue {C131}
cysteine residue {C131}
MODIFICATION: cysteine residue {C120}
cysteine residue {C157}
MODIFICATION: cysteine residue {C92}
cysteine residue {C165}
MODIFICATION: cysteine residue {C89}
N-glycosylation site {N175}
cysteine residue {C221}
MODIFICATION: cysteine residue {C226}
cysteine residue {C226}
MODIFICATION: cysteine residue {C221}
cysteine residue {C227}
MODIFICATION: cysteine residue {C250}
cysteine residue {C250}
MODIFICATION: cysteine residue {C227}
N-glycosylation site {N335}
cysteine residue {C385}
MODIFICATION: cysteine residue {C431}
N-glycosylation site {N395}
cysteine residue {C431}
MODIFICATION: cysteine residue {C385}
N-glycosylation site {N520}
cysteine residue {C584}
MODIFICATION: cysteine residue {C588}
cysteine residue {C588}
MODIFICATION: cysteine residue {C584}
cysteine residue {C594}
MODIFICATION: cysteine residue {C607}
cysteine residue {C607}
MODIFICATION: cysteine residue {C594}
Database Correlations
OMIM correlations
MORBIDMAP 607608
UniProt P17405
Pfam PF00149
Entrez Gene 6609
Kegg hsa:6609
ENZYME 3.1.4.12
References
- UniProt :accession P17405
- GeneReviews
http://www.ncbi.nlm.nih.gov/sites/genetests/lab/gene/SMPD1