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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot Q00266: Variant p.Arg264His

S-adenosylmethionine synthase isoform type-1
Gene: MAT1A
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Variant information Variant position: help 264 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 Arginine (R) to Histidine (H) at position 264 (R264H, p.Arg264His). 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 large size and basic (R) to medium size and polar (H) 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 MATD; dominant mutation. Any additional useful information about the variant.
Other resources: help Links to websites of interest for the variant.


Sequence information Variant position: help 264 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 395 The length of the canonical sequence.
Location on the sequence: help LQPSGRFVIGGPQGDAGVTG R KIIVDTYGGWGAHGGGAFSG 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                         LQPSGRFVIGGPQGDAGVTGRKIIVDTYGGWGAHGGGAFSG

Mouse                         LQPSGRFVIGGPQGDAGVTGRKIIVDTYGGWGAHGGGAFSG

Rat                           LQPSGRFVIGGPQGDAGVTGRKIIVDTYGGWGAHGGGAFSG

Bovine                        LQPSGRFVIGGPQGDAGVTGRKIIVDTYGGWGAHGGGAFSG

Caenorhabditis elegans        INPCGTFIVGGPMGDAGVTGRKIIVDTYGGWGAHGGGAFSG

Baker's yeast                 IQPSGRFVIGGPQGDAGLTGRKIIVDAYGGASSVGGGAFSG
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 – 395 S-adenosylmethionine synthase isoform type-1
Binding site 258 – 258 in other chain
Binding site 258 – 258
Binding site 264 – 265 in other chain
Binding site 281 – 281



Literature citations
Dominant inheritance of isolated hypermethioninemia is associated with a mutation in the human methionine adenosyltransferase 1A gene.
Chamberlin M.E.; Ubagai T.; Mudd S.H.; Levy H.L.; Chou J.Y.;
Am. J. Hum. Genet. 60:540-546(1997)
Cited for: VARIANT MATD HIS-264; Methionine adenosyltransferase I/III deficiency: novel mutations and clinical variations.
Chamberlin M.E.; Ubagai T.; Mudd S.H.; Thomas J.; Pao V.Y.; Nguyen T.K.; Levy H.L.; Greene C.; Freehauf C.; Chou J.Y.;
Am. J. Hum. Genet. 66:347-355(2000)
Cited for: VARIANTS MATD ASN-38; CYS-264; HIS-264; MET-322; ARG-336 AND ALA-344; CHARACTERIZATION OF VARIANTS MATD ASN-38; CYS-264; HIS-264; MET-322; ARG-336 AND ALA-344; CATALYTIC ACTIVITY; FUNCTION; PATHWAY;
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.