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UniProtKB/Swiss-Prot P20273: Variant p.Tyr639His

B-cell receptor CD22
Gene: CD22
Chromosomal location: 19q13.1
Variant information

Variant position:  639
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 Tyrosine (Y) to Histidine (H) at position 639 (Y639H, p.Tyr639His).
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 large size and aromatic (Y) to medium size and polar (H)
The physico-chemical property of the reference and variant residues and the change implicated.

BLOSUM score:  2
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

Other resources:  
Links to websites of interest for the variant.



Sequence information

Variant position:  639
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  847
The length of the canonical sequence.

Location on the sequence:   DANPPVSHYTWFDWNNQSLP  Y HSQKLRLEPVKVQHSGAYWC
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                         DANPPVSHYTWFDWNNQSLPYHSQKLRLEPVKVQHSGAYWC

Mouse                         DANPPISQYTWFDSSGQDLHSSGQKLRLEPLEVQHTGSYRC

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 20 – 847 B-cell receptor CD22
Topological domain 20 – 687 Extracellular
Domain 593 – 676 Ig-like C2-type 6
Glycosylation 634 – 634 N-linked (GlcNAc...) asparagine
Disulfide bond 616 – 659


Literature citations

cDNA cloning of the B cell membrane protein CD22: a mediator of B-B cell interactions.
Wilson G.L.; Fox C.H.; Fauci A.S.; Kehrl J.H.;
J. Exp. Med. 173:137-146(1991)
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM CD22-BETA); VARIANT HIS-639;

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.