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UniProtKB/Swiss-Prot Q9NP91: Variant p.Thr199Met

Sodium- and chloride-dependent transporter XTRP3
Gene: SLC6A20
Variant information

Variant position:  199
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Type of variant:  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:  From Threonine (T) to Methionine (M) at position 199 (T199M, p.Thr199Met).
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 polar (T) to medium size and hydrophobic (M)
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

Variant description:  Common variant that contributes to hyperglycinuria and iminoglycinuria in patients carrying variants in SLC36A2, SLC6A19 or SLC6A18; results in SLC6A20 inactivation due to a 8-fold decrease of Vmax.
Any additional useful information about the variant.

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



Sequence information

Variant position:  199
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  592
The length of the canonical sequence.

Location on the sequence:   LVVYLCILRGTESTGKVVYF  T ASLPYCVLIIYLIRGLTLHG
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.

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 1 – 592 Sodium- and chloride-dependent transporter XTRP3
Transmembrane 195 – 215 Helical; Name=5
Alternative sequence 195 – 231 Missing. In isoform 2.


Literature citations

Iminoglycinuria and hyperglycinuria are discrete human phenotypes resulting from complex mutations in proline and glycine transporters.
Broer S.; Bailey C.G.; Kowalczuk S.; Ng C.; Vanslambrouck J.M.; Rodgers H.; Auray-Blais C.; Cavanaugh J.A.; Broer A.; Rasko J.E.;
J. Clin. Invest. 118:3881-3892(2008)
Cited for: FUNCTION; TISSUE SPECIFICITY; VARIANT MET-199; CHARACTERIZATION OF VARIANT MET-199; INVOLVEMENT IN HG AND IG;

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.