ID:ASM_HUMAN DESCRIPTION: RecName: Full=Sphingomyelin phosphodiesterase; EC=3.1.4.12; AltName: Full=Acid sphingomyelinase; Short=aSMase; Flags: Precursor; FUNCTION: Converts sphingomyelin to ceramide. Also has phospholipase C activities toward 1,2-diacylglycerolphosphocholine and 1,2-diacylglycerolphosphoglycerol. Isoform 2 and isoform 3 have lost catalytic activity. CATALYTIC ACTIVITY: Sphingomyelin + H(2)O = N-acylsphingosine + phosphocholine. SUBUNIT: Monomer. SUBCELLULAR LOCATION: Lysosome. POLYMORPHISM: A common polymorphism arises from a variable number of hexanucleotide repeat sequence within the signal peptide region. DISEASE: Defects in SMPD1 are the cause of Niemann-Pick disease type A (NPDA) [MIM:257200]; also known as Niemann-Pick disease classical infantile form. It is an early-onset lysosomal storage disorder caused by failure to hydrolyze sphingomyelin to ceramide. It results in the accumulation of sphingomyelin and other metabolically related lipids in reticuloendothelial and other cell types throughout the body, leading to cell death. Niemann-Pick disease type A is a primarily neurodegenerative disorder characterized by onset within the first year of life, mental retardation, digestive disorders, failure to thrive, major hepatosplenomegaly, and severe neurologic symptoms. The severe neurological disorders and pulmonary infections lead to an early death, often around the age of four. Clinical features are variable. A phenotypic continuum exists between type A (basic neurovisceral) and type B (purely visceral) forms of Niemann-Pick disease, and the intermediate types encompass a cluster of variants combining clinical features of both types A and B. DISEASE: Defects in SMPD1 are the cause of Niemann-Pick disease type B (NPDB) [MIM:607616]; also known as Niemann-Pick disease visceral form. It is a late-onset lysosomal storage disorder caused by failure to hydrolyze sphingomyelin to ceramide. It results in the accumulation of sphingomyelin and other metabolically related lipids in reticuloendothelial and other cell types throughout the body, leading to cell death. Clinical signs involve only visceral organs. The most constant sign is hepatosplenomegaly which can be associated with pulmonary symptoms. Patients remain free of neurologic manifestations. However, a phenotypic continuum exists between type A (basic neurovisceral) and type B (purely visceral) forms of Niemann-Pick disease, and the intermediate types encompass a cluster of variants combining clinical features of both types A and B. In Niemann-Pick disease type B, onset of the first symptoms occurs in early childhood and patients can survive into adulthood. MISCELLANEOUS: There are two types of sphingomyelinases: ASM (acid), and NSM (neutral). SIMILARITY: Belongs to the acid sphingomyelinase family. SIMILARITY: Contains 1 saposin B-type domain. WEB RESOURCE: Name=GeneReviews; URL="http://www.ncbi.nlm.nih.gov/sites/GeneTests/lab/gene/SMPD1"; WEB RESOURCE: Name=Mendelian genes sphingomyelin phosphodiesterase 1, acid lysosomal (SMPD1); Note=Leiden Open Variation Database (LOVD); URL="http://www.lovd.nl/SMPD1";
The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.
ModBase Predicted Comparative 3D Structure on P17405
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Orthologous Genes in Other Species
Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
Gene Ontology (GO) Annotations with Structured Vocabulary
Molecular Function: GO:0004767 sphingomyelin phosphodiesterase activity GO:0005515 protein binding GO:0008270 zinc ion binding GO:0016787 hydrolase activity GO:0016798 hydrolase activity, acting on glycosyl bonds GO:0046872 metal ion binding GO:0061750 acid sphingomyelin phosphodiesterase activity
Biological Process: GO:0006684 sphingomyelin metabolic process GO:0006685 sphingomyelin catabolic process GO:0006687 glycosphingolipid metabolic process GO:0007165 signal transduction GO:0007399 nervous system development GO:0008152 metabolic process GO:0023021 termination of signal transduction GO:0035307 positive regulation of protein dephosphorylation GO:0042220 response to cocaine GO:0042493 response to drug GO:0043065 positive regulation of apoptotic process GO:0043407 negative regulation of MAP kinase activity GO:0046513 ceramide biosynthetic process
US Server
Sequence and Links to Tools and Databases 
Common Gene Haplotype Alleles 
