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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot P17405: Variant p.Val132Ala

Sphingomyelin phosphodiesterase
Gene: SMPD1
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Variant information Variant position: help 132 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Type of variant: help LP/P [Disclaimer] The variants are classified into three categories: LP/P, LB/B and US.
  • LP/P: likely pathogenic or pathogenic.
  • LB/B: likely benign or benign.
  • US: uncertain significance
Residue change: help From Valine (V) to Alanine (A) at position 132 (V132A, p.Val132Ala). Indicates the amino acid change of the variant. The one-letter and three-letter codes for amino acids used in UniProtKB/Swiss-Prot are those adopted by the commission on Biochemical Nomenclature of the IUPAC-IUB.
Physico-chemical properties: help Change from medium size and hydrophobic (V) to small size and hydrophobic (A) The physico-chemical property of the reference and variant residues and the change implicated.
BLOSUM score: help 0 The score within a Blosum matrix for the corresponding wild-type to variant amino acid change. The log-odds score measures the logarithm for the ratio of the likelihood of two amino acids appearing by chance. The Blosum62 substitution matrix is used. This substitution matrix contains scores for all possible exchanges of one amino acid with another:
  • Lowest score: -4 (low probability of substitution).
  • Highest score: 11 (high probability of substitution).
More information can be found on the following page
Variant description: help In NPDB; expresses protein level comparable to wild-type SMPD1 expressing cells; retains 13% residual enzyme activity. Any additional useful information about the variant.


Sequence information Variant position: help 132 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 631 The length of the canonical sequence.
Location on the sequence: help ARVGSVAIKLCNLLKIAPPA V CQSIVHLFEDDMVEVWRRSV The residue change on the sequence. Unless the variant is located at the beginning or at the end of the protein sequence, both residues upstream (20) and downstream (20) of the variant will be shown.
Residue conservation: help The multiple alignment of the region surrounding the variant against various orthologous sequences. 
Human                         ARVGSVAIKLCNLLKIAPPAVCQSIVHLFEDDMVEVWRRSV

Mouse                         ARVGSVAIKICKMLNIAPLDVCQSAVHLFEDDVVEVWTRSV

Bovine                        AWVGSVAIKLCVLLKIAPPAVCQSAVQLFEDDMVEVWTRSV
Sequence annotation in neighborhood: help The regions or sites of interest surrounding the variant. In general the features listed are posttranslational modifications, binding sites, enzyme active sites, local secondary structure or other characteristics reported in the cited references. The "Sequence annotation in neighborhood" lines have a fixed format:
  • Type: the type of sequence feature.
  • Positions: endpoints of the sequence feature.
  • Description: contains additional information about the feature.
TypePositionsDescription
Chain 47 – 631 Sphingomyelin phosphodiesterase
Domain 87 – 171 Saposin B-type
Disulfide bond 91 – 167
Disulfide bond 94 – 159
Disulfide bond 122 – 133
Mutagenesis 151 – 151 S -> A. No effect on sphingomyelin phosphodiesterase activity. No effect on subcellular location. No effect on phosphorylation by PRKCD.
Helix 130 – 150



Literature citations
Functional in vitro characterization of 14 SMPD1 mutations identified in Italian patients affected by Niemann Pick type B disease.
Dardis A.; Zampieri S.; Filocamo M.; Burlina A.; Bembi B.; Pittis M.G.;
Hum. Mutat. 26:164-164(2005)
Cited for: VARIANTS NPDB ALA-132 AND TYR-565; CHARACTERIZATION OF VARIANTS NPDB PRO-105; ALA-132; PRO-227; CYS-246; THR-283; TYR-565; HIS-602 AND PRO-602;
Disclaimer: Any medical or genetic information present in this entry is provided for research, educational and informational purposes only. They are not in any way intended to be used as a substitute for professional medical advice, diagnostic, treatment or care.