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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot P35520: Variant p.Thr257Met

Cystathionine beta-synthase
Gene: CBS
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Variant information Variant position: help 257 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 Threonine (T) to Methionine (M) at position 257 (T257M, p.Thr257Met). 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 polar (T) to medium size and hydrophobic (M) The physico-chemical property of the reference and variant residues and the change implicated.
BLOSUM score: help -1 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 CBSD; moderate to severe form; protein expression is comparable to wild-type; significant decrease of enzyme activity. Any additional useful information about the variant.
Other resources: help Links to websites of interest for the variant.


Sequence information Variant position: help 257 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 551 The length of the canonical sequence.
Location on the sequence: help ADEILQQCDGKLDMLVASVG T GGTITGIARKLKEKCPGCRI 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                         ADEILQQCD-----GKLDMLVASVGTGGTITGIARKLKEKCPGCRI

Mouse                         AEEILQQCD-----GKLDMLVASAGTGGTITGIARKLKEKC

Rat                           AEEILQQCD-----GKVDMLVASAGTGGTITGIARKLKEKC

Rabbit                        AEEILQQCD-----GKLDMLVASAGTGGTITGIARKLKEKC

Slime mold                    AEELLEQCE-----GKIDMIVCTAGTGGTITGIARKIKERL

Baker's yeast                 GREIQRQLEDLNLFDNLRAVVAGAGTGGTISGISKYLKEQN
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 1 – 551 Cystathionine beta-synthase
Binding site 256 – 260
Mutagenesis 272 – 272 C -> A. Reduced heme content and cystathionine beta-synthase activity.
Mutagenesis 275 – 275 C -> S. Reduced heme content and cystathionine beta-synthase activity.
Beta strand 256 – 258



Literature citations
The molecular basis of homocystinuria due to cystathionine beta-synthase deficiency in Italian families, and report of four novel mutations.
Sebastio G.; Sperandeo M.P.; Panico M.; de Franchis R.; Kraus J.P.; Andria G.;
Am. J. Hum. Genet. 56:1324-1333(1995)
Cited for: VARIANTS CBSD SER-88; GLN-125 AND MET-257; Identification and functional analysis of cystathionine beta-synthase gene mutations in patients with homocystinuria.
Lee S.-J.; Lee D.H.; Yoo H.-W.; Koo S.K.; Park E.-S.; Park J.-W.; Lim H.G.; Jung S.-C.;
J. Hum. Genet. 50:648-654(2005)
Cited for: VARIANTS CBSD GLN-154; VAL-155; ASP-234 DEL; MET-257; THR-288; CYS-336; SER-347 AND MET-353; VARIANT CYS-18; CHARACTERIZATION OF VARIANTS CBSD GLN-154; VAL-155; ASP-234 DEL; MET-257; THR-288; CYS-336; SER-347 AND MET-353; CHARACTERIZATION OF VARIANT CYS-18;
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.