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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot P51787: Variant p.Leu250His

Potassium voltage-gated channel subfamily KQT member 1
Gene: KCNQ1
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Variant information Variant position: help 250 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 Leucine (L) to Histidine (H) at position 250 (L250H, p.Leu250His). 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 medium size and polar (H) 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 LQT1; complete loss of outward potassium current; enhances outward potassium current when co-transfected with wild type; decreases plasma membrane localization. Any additional useful information about the variant.
Other resources: help Links to websites of interest for the variant.


Sequence information Variant position: help 250 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 676 The length of the canonical sequence.
Location on the sequence: help IRFLQILRMLHVDRQGGTWR L LGSVVFIHRQELITTLYIGF 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                         IRFLQILRMLHVDRQGGTWRLLGSVVFIHRQELITTLYIGF

Mouse                         IRFLQILRMLHVDRQGGTWRLLGSVVFIHRQELITTLYIGF

Rat                           IRFLQILRMLHVDRQGGTWRLLGSVVFIHRQELITTLYIGF

Pig                           IRFLQILRMLHVDRQGGTWRLLGSVVFIHRQELITTLYIGF

Rabbit                        IRFLQILRMLHVDRQGGTWRLLGSVVFIHRQELITTLYIGF

Xenopus laevis                IRFLQILRMLHVDRQGGTWRLLGSVVFIHRQELITTLYIGF
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 – 676 Potassium voltage-gated channel subfamily KQT member 1
Topological domain 249 – 261 Cytoplasmic
Mutagenesis 231 – 231 R -> A. Strongly inhibits SLC5A3 transporter activity.
Helix 246 – 284



Literature citations
Genomic organization and mutational analysis of KVLQT1, a gene responsible for familial long QT syndrome.
Itoh T.; Tanaka T.; Nagai R.; Kikuchi K.; Ogawa S.; Okada S.; Yamagata S.; Yano K.; Yazaki Y.; Nakamura Y.;
Hum. Genet. 103:290-294(1998)
Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] (ISOFORMS 1 AND 2); VARIANTS LQT1 ASN-242; HIS-250; SER-314 AND MET-587; VARIANT SER-643; Cellular mechanisms of mutations in Kv7.1: auditory functions in Jervell and Lange-Nielsen syndrome vs. Romano-Ward syndrome.
Mousavi Nik A.; Gharaie S.; Jeong Kim H.;
Front. Cell. Neurosci. 9:32-32(2015)
Cited for: CHARACTERIZATION OF VARIANTS LQT1 ASN-242; PRO-243; HIS-250; VAL-306; ASN-317; ASP-586 AND MET-619; CHARACTERIZATION OF VARIANTS JLNS1 PHE-248; ILE-311; MET-322 AND ASP-589;
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.