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UniProtKB/Swiss-Prot B7U540: Variant p.Thr354Met

Inward rectifier potassium channel 18
Gene: KCNJ18
Variant information

Variant position:  354
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Type of variant:  Disease [Disclaimer]
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 Threonine (T) to Methionine (M) at position 354 (T354M, p.Thr354Met).
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

Involvement in disease:  Thyrotoxic periodic paralysis 2 (TTPP2) [MIM:613239]: A sporadic muscular disorder characterized by episodic weakness and hypokalemia during a thyrotoxic state. It is clinically similar to hereditary hypokalemic periodic paralysis, except for the fact that hyperthyroidism is an absolute requirement for disease manifestation. The disease presents with recurrent episodes of acute muscular weakness of the four extremities that vary in severity from paresis to complete paralysis. Attacks are triggered by ingestion of a high carbohydrate load or strenuous physical activity followed by a period of rest. Thyrotoxic periodic paralysis can occur in association with any cause of hyperthyroidism, but is most commonly associated with Graves disease. {ECO:0000269|PubMed:20074522, ECO:0000269|PubMed:21665951, ECO:0000269|PubMed:25885757, ECO:0000269|PubMed:27178871}. Note=Disease susceptibility is associated with variations affecting the gene represented in this entry.
The name and a short description of the disease associated with the variant. For more information about the disease, the user can refer to OMIM, following the link provided after the disease acronym.

Variant description:  In TTPP2; small decrease in current density.
Any additional useful information about the variant.

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



Sequence information

Variant position:  354
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  433
The length of the canonical sequence.

Location on the sequence:   EKNQYKIDYSHFHKTYEVPS  T PRCSAKDLVENKFLLPSANS
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 – 433 Inward rectifier potassium channel 18
Topological domain 178 – 433 Cytoplasmic
Mutagenesis 354 – 354 T -> E. Decreases the single-channel open probability (Po) without altering its conductance.


Literature citations

Mutations in potassium channel Kir2.6 cause susceptibility to thyrotoxic hypokalemic periodic paralysis.
Ryan D.P.; da Silva M.R.; Soong T.W.; Fontaine B.; Donaldson M.R.; Kung A.W.; Jongjaroenprasert W.; Liang M.C.; Khoo D.H.; Cheah J.S.; Ho S.C.; Bernstein H.S.; Maciel R.M.; Brown R.H. Jr.; Ptacek L.J.;
Cell 140:88-98(2010)
Cited for: NUCLEOTIDE SEQUENCE [MRNA]; FUNCTION; INDUCTION BY TRIIODOTHYRONINE; TISSUE SPECIFICITY; PHOSPHORYLATION; VARIANTS TTPP2 MET-140; HIS-205; MET-354 AND ARG-366; CHARACTERIZATION OF VARIANTS TTPP2 HIS-205; MET-354 AND ARG-366; MUTAGENESIS OF THR-354; VARIANTS 39-ARG-ARG-40 DELINS GLN-HIS AND VAL-249;

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.