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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot Q8IU80: Variant p.Arg774Cys

Transmembrane protease serine 6
Gene: TMPRSS6
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Variant information Variant position: help 774 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 Cysteine (C) at position 774 (R774C, p.Arg774Cys). 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 (C) The physico-chemical property of the reference and variant residues and the change implicated.
BLOSUM score: help -3 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 IRIDA; reduced proteolytic processing; reduced expression to plasma membrane; does not affect binding to HJV. Any additional useful information about the variant.
Other resources: help Links to websites of interest for the variant.


Sequence information Variant position: help 774 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 811 The length of the canonical sequence.
Location on the sequence: help KKDACQGDSGGPLVCKALSG R WFLAGLVSWGLGCGRPNYFG 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                         KKDACQGDSGGPLVCKALSGRWFLAGLVSWGLGCGRPNYFG

Mouse                         KKDACQGDSGGPLVCREPSGRWFLAGLVSWGLGCGRPNFFG
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 – 811 Transmembrane protease serine 6
Topological domain 77 – 811 Extracellular
Domain 577 – 811 Peptidase S1
Active site 762 – 762 Charge relay system
Disulfide bond 758 – 787
Alternative sequence 462 – 811 Missing. In isoform 3.
Mutagenesis 762 – 762 S -> A. Does not undergo proteolytic processing.



Literature citations
The serine protease matriptase-2 (TMPRSS6) inhibits hepcidin activation by cleaving membrane hemojuvelin.
Silvestri L.; Pagani A.; Nai A.; De Domenico I.; Kaplan J.; Camaschella C.;
Cell Metab. 8:502-511(2008)
Cited for: FUNCTION; INTERACTION WITH HJV; SUBCELLULAR LOCATION; PROTEOLYTIC PROCESSING; CHARACTERIZATION OF VARIANT IRIDA CYS-774; Mutations in TMPRSS6 cause iron-refractory iron deficiency anemia (IRIDA).
Finberg K.E.; Heeney M.M.; Campagna D.R.; Aydinok Y.; Pearson H.A.; Hartman K.R.; Mayo M.M.; Samuel S.M.; Strouse J.J.; Markianos K.; Andrews N.C.; Fleming M.D.;
Nat. Genet. 40:569-571(2008)
Cited for: VARIANTS IRIDA ARG-442; ASN-521 AND CYS-774; FUNCTION IN IRON HOMEOSTASIS;
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.