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UniProtKB/Swiss-Prot P20062: Variant p.Met198Thr

Transcobalamin-2
Gene: TCN2
Chromosomal location: 22q12.2
Variant information

Variant position:  198
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Type of variant:  Polymorphism
The variants are classified into three categories: Disease, Polymorphism and Unclassified.
  • Disease: Variants implicated in disease according to literature reports.
  • Polymorphism: Variants not reported to be implicated in disease.
  • Unclassified: Variants with uncertain implication in disease according to literature reports. Evidence against or in favor of a pathogenic role is limited and/or conflicting.

Residue change:  From Methionine (M) to Threonine (T) at position 198 (M198T, p.Met198Thr).
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:  Change from medium size and hydrophobic (M) to medium size and polar (T)
The physico-chemical property of the reference and variant residues and the change implicated.

BLOSUM score:  -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

Polymorphism:  Pro/Arg-259 polymorphism affects TCN2 plasma concentration and may interfere in vitamin B(12) cellular availability and homocysteine metabolism (PubMed:11159542).
Additional information on the polymorphism described.



Sequence information

Variant position:  198
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  427
The length of the canonical sequence.

Location on the sequence:   KLLYAVEPFHQGHHSVDTAA  M AGLAFTCLKRSNFNPGRRQR
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: 
The multiple alignment of the region surrounding the variant against various orthologous sequences.

Human                         KLLYAVE--PF-HQGHHSVDTAAMAGLAFTCLKRSNFNPGRRQR

Mouse                         KLLYAVEHDYFTYQGHVSVDTEAMAGLALTCLERFNFNSDL

Rat                           KLLYAVEHDYFTYQGHLSVDTEAMAGLAFTCLERFNFNSDL

Bovine                        KLLYAVEHKPHLLQDHVSVDTMAMAGMAFSCLELSNLNPKQ

Sequence annotation in neighborhood:  
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 19 – 427 Transcobalamin-2
Metal binding 190 – 190 Cobalt (cobalamin axial ligand)
Disulfide bond 21 – 267
Disulfide bond 116 – 309
Disulfide bond 165 – 205
Helix 193 – 208


Literature citations

The cDNA sequence and the deduced amino acid sequence of human transcobalamin II show homology with rat intrinsic factor and human transcobalamin I.
Platica O.; Janeczko R.; Quadros E.V.; Regec A.; Romain R.; Rothenberg S.P.;
J. Biol. Chem. 266:7860-7863(1991)
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1); VARIANTS THR-198; LEU-219; PRO-259 AND SER-376;

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.