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UniProtKB/Swiss-Prot O15439: Variant p.Leu18Ile

Multidrug resistance-associated protein 4
Gene: ABCC4
Variant information

Variant position:  18
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Type of variant:  Polymorphism
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 Leucine (L) to Isoleucine (I) at position 18 (L18I, p.Leu18Ile).
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:  Similar physico-chemical property. Both residues are medium size and hydrophobic.
The physico-chemical property of the reference and variant residues and the change implicated.

BLOSUM score:  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

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



Sequence information

Variant position:  18
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  1325
The length of the canonical sequence.

Location on the sequence:   MLPVYQEVKPNPLQDAN  L CSRVFFWWLNPLFKIGHKRR
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 – 1325 Multidrug resistance-associated protein 4


Literature citations

Isolation of MOAT-B, a widely expressed multidrug resistance-associated protein/canalicular multispecific organic anion transporter-related transporter.
Lee K.; Belinsky M.G.; Bell D.W.; Testa J.R.; Kruh G.D.;
Cancer Res. 58:2741-2747(1998)
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1); VARIANT ILE-18;

Expression of MRP4 confers resistance to ganciclovir and compromises bystander cell killing.
Adachi M.; Sampath J.; Lan L.B.; Sun D.; Hargrove P.; Flatley R.; Tatum A.; Edwards M.Z.; Wezeman M.; Matherly L.; Drake R.; Schuetz J.;
J. Biol. Chem. 277:38998-39004(2002)
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1); VARIANT ILE-18;

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.