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UniProtKB/Swiss-Prot P21439: Variant p.Ser320Phe

Phosphatidylcholine translocator ABCB4
Gene: ABCB4
Variant information

Variant position:  320
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Type of variant:  Unclassified
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 Serine (S) to Phenylalanine (F) at position 320 (S320F, p.Ser320Phe).
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 small size and polar (S) to large size and aromatic (F)
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

Variant description:  In ICP3, GBD1 and PFIC3; unknown pathological significance; does not alter plasma membrane location; does not inhibit efflux activity for PC.
Any additional useful information about the variant.

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



Sequence information

Variant position:  320
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  1286
The length of the canonical sequence.

Location on the sequence:   SMGIAFLLIYASYALAFWYG  S TLVISKEYTIGNAMTVFFSI
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 – 1286 Phosphatidylcholine translocator ABCB4
Topological domain 319 – 332 Extracellular
Domain 57 – 359 ABC transmembrane type-1 1


Literature citations

Molecular mechanistic explanation for the spectrum of cholestatic disease caused by the S320F variant of ABCB4.
Andress E.J.; Nicolaou M.; Romero M.R.; Naik S.; Dixon P.H.; Williamson C.; Linton K.J.;
Hepatology 59:1921-1931(2014)
Cited for: FUNCTION; SUBCELLULAR LOCATION; CHARACTERIZATION OF VARIANTS PFIC3 VAL-286 AND PHE-320; MUTAGENESIS OF ALA-953;

MDR3 gene defect in adults with symptomatic intrahepatic and gallbladder cholesterol cholelithiasis.
Rosmorduc O.; Hermelin B.; Poupon R.;
Gastroenterology 120:1459-1467(2001)
Cited for: VARIANTS GBD1 PHE-320 AND SER-1168; VARIANT ALA-175;

ABCB4 gene mutation-associated cholelithiasis in adults.
Rosmorduc O.; Hermelin B.; Boelle P.Y.; Parc R.; Taboury J.; Poupon R.;
Gastroenterology 125:452-459(2003)
Cited for: VARIANTS GBD1 ILE-165; THR-301; PHE-320; ASP-528; GLN-591 AND SER-1168; VARIANTS ALA-175; GLN-590; GLY-652; SER-742; GLN-788 AND THR-934;

Sequence analysis of bile salt export pump (ABCB11) and multidrug resistance p-glycoprotein 3 (ABCB4, MDR3) in patients with intrahepatic cholestasis of pregnancy.
Pauli-Magnus C.; Lang T.; Meier Y.; Zodan-Marin T.; Jung D.; Breymann C.; Zimmermann R.; Kenngott S.; Beuers U.; Reichel C.; Kerb R.; Penger A.; Meier P.J.; Kullak-Ublick G.A.;
Pharmacogenetics 14:91-102(2004)
Cited for: VARIANTS ALA-175; GLY-652 AND MET-775; VARIANTS ICP3 PHE-320; ASP-528 AND GLU-762;

Molecular characterization and structural implications of 25 new ABCB4 mutations in progressive familial intrahepatic cholestasis type 3 (PFIC3).
Degiorgio D.; Colombo C.; Seia M.; Porcaro L.; Costantino L.; Zazzeron L.; Bordo D.; Coviello D.A.;
Eur. J. Hum. Genet. 15:1230-1238(2007)
Cited for: VARIANTS PFIC3 GLU-126; PRO-250; VAL-286; PHE-320; LEU-357; VAL-364; HIS-403; ALA-475; THR-511; LYS-558; ALA-593; VAL-630; PRO-701; ILE-715; GLU-723; THR-726; VAL-737; ASP-840; SER-954 AND THR-1193; VARIANTS ALA-175; GLN-590 AND MET-775;

Clinical features and genotype-phenotype correlations in children with progressive familial intrahepatic cholestasis type 3 related to ABCB4 mutations.
Colombo C.; Vajro P.; Degiorgio D.; Coviello D.A.; Costantino L.; Tornillo L.; Motta V.; Consonni D.; Maggiore G.; Balli F.; Berardi S.; Calacoci M.; Castellano E.; Marazzi M.G.; Gaslini G.; D'Antiga L.; Ferretti E.; Giannini A.; Indolfi G.; Iorio R.; Martelossi S.; Moretti C.; Nebbia G.; Oliveri F.; Poggiani C.; Raggi M.; Riva S.; Sciveres M.; Torre G.; Zancan L.;
J. Pediatr. Gastroenterol. Nutr. 52:73-83(2011)
Cited for: VARIANTS PFIC3 ARG-70; VAL-73; PHE-320 AND HIS-403; VARIANT GLY-652;

Aspects of liver pathology in adult patients with MDR3/ABCB4 gene mutations.
Wendum D.; Barbu V.; Rosmorduc O.; Arrive L.; Flejou J.F.; Poupon R.;
Virchows Arch. 460:291-298(2012)
Cited for: VARIANTS GBD1 MET-34; GLY-47; VAL-286 AND ASP-528; VARIANTS GLN-47; ALA-175; PHE-320; GLN-406; MET-775 AND THR-964;

Genotype-phenotype relationships in the low-phospholipid-associated cholelithiasis syndrome: a study of 156 consecutive patients.
Poupon R.; Rosmorduc O.; Boelle P.Y.; Chretien Y.; Corpechot C.; Chazouilleres O.; Housset C.; Barbu V.;
Hepatology 58:1105-1110(2013)
Cited for: VARIANTS GBD1 GLY-47; HIS-71; VAL-73; CYS-78; PHE-99; SER-124; SER-154; ILE-165; VAL-286; THR-301; PHE-320; GLY-406; SER-510; THR-511; LYS-513; ASP-528; PHE-541; HIS-545; HIS-549; THR-589; GLN-591; MET-593; LYS-647; LEU-726; LEU-729; VAL-975 AND TRP-1084; VARIANTS ALA-175; GLN-590; GLN-788 AND THR-934;

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.