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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot P21217: Variant p.Leu20Arg

3-galactosyl-N-acetylglucosaminide 4-alpha-L-fucosyltransferase FUT3
Gene: FUT3
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Variant information Variant position: help 20 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Type of variant: help LB/B 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 Leucine (L) to Arginine (R) at position 20 (L20R, p.Leu20Arg). 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 (L) to large size and basic (R) The physico-chemical property of the reference and variant residues and the change implicated.
BLOSUM score: help -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

Polymorphism: help Genetic variations in FUT3 define the Lewis blood group system (LE) [MIM:618983]. FUT3 catalyzes the addition of fucose to precursor polysaccharides in the last step of Lewis antigen biosynthesis. Variations in this gene are responsible for the majority of Lewis antigen-negative phenotypes (Le(-)). Additional information on the polymorphism described.
Variant description: help In Le(-) individuals. Any additional useful information about the variant.
Other resources: help Links to websites of interest for the variant.


Sequence information Variant position: help 20 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 361 The length of the canonical sequence.
Location on the sequence: help MDPLGAAKPQWPWRRCLAA L LFQLLVAVCFFSYLRVSRDD 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                         MDPLGAAKPQWPWRRCLAALLFQLLVAVCFFSYLRVSRDD

Chimpanzee                    MDPLGAAKPQWPWRRCLAALLFQLLVAVCFFSYLRVSRDD

Bovine                        MYPPGCAKVKCSWHHCLPGLLLQLLLALCFFSYLRMSQEK

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 – 361 3-galactosyl-N-acetylglucosaminide 4-alpha-L-fucosyltransferase FUT3
Transmembrane 16 – 34 Helical; Signal-anchor for type II membrane protein



Literature citations
Alpha (1,3/1,4)fucosyltransferase (FucT-III) gene is inactivated by a single amino acid substitution in Lewis histo-blood type negative individuals.
Nishihara S.; Yazawa S.; Iwasaki H.; Nakazato M.; Kudo T.; Ando T.; Narimatsu H.;
Biochem. Biophys. Res. Commun. 196:624-631(1993)
Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]; VARIANTS LE(-) ARG-20; SER-170 AND ALA-336; VARIANTS TRP-68 AND THR-105; Submission
SeattleSNPs variation discovery resource;
Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]; VARIANTS LE(-) ARG-20; ASN-162; SER-170; ARG-223 AND MET-270; VARIANTS SER-5; CYS-160; MET-325 AND GLN-327; VARIANTS TRP-68 AND THR-105; Analysis of Lewis fucosyltransferase genes from the human gastric mucosa of Lewis-positive and -negative individuals.
Koda Y.; Kimura H.; Mekada E.;
Blood 82:2915-2919(1993)
Cited for: VARIANTS LE(-) ARG-20 AND SER-170; Molecular basis for Lewis alpha(1,3/1,4)-fucosyltransferase gene deficiency (FUT3) found in Lewis-negative Indonesian pedigrees.
Mollicone R.; Reguigne I.; Kelly R.J.; Fletcher A.; Watt J.; Chatfield S.; Aziz A.; Cameron H.S.; Weston B.W.; Lowe J.B.; Oriol R.;
J. Biol. Chem. 269:20987-20994(1994)
Cited for: VARIANTS LE(-) ARG-20 AND LYS-356; DNA sequencing and screening for point mutations in the human Lewis 'FUT3' gene enables molecular genotyping of the human Lewis blood group system.
Elmgren A.; Boerjeson C.; Svensson L.; Rydberg L.; Larson G.;
Vox Sang. 70:97-103(1996)
Cited for: VARIANTS LE(-) ARG-20; ARG-68; MET-105 AND LYS-356;
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.