Home  |  Contact

UniProtKB/Swiss-Prot P55157: Variant p.Asp169Val

Microsomal triglyceride transfer protein large subunit
Gene: MTTP
Variant information

Variant position:  169
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 Aspartate (D) to Valine (V) at position 169 (D169V, p.Asp169Val).
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 acidic (D) to medium size and hydrophobic (V)
The physico-chemical property of the reference and variant residues and the change implicated.

BLOSUM score:  -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

Involvement in disease:  Abetalipoproteinemia (ABL) [MIM:200100]: An autosomal recessive disorder of lipoprotein metabolism. Affected individuals produce virtually no circulating apolipoprotein B-containing lipoproteins (chylomicrons, VLDL, LDL, lipoprotein(A)). Malabsorption of the antioxidant vitamin E occurs, leading to spinocerebellar and retinal degeneration. {ECO:0000269|PubMed:10679949, ECO:0000269|PubMed:10946006, ECO:0000269|PubMed:22236406, ECO:0000269|PubMed:23475612, ECO:0000269|PubMed:25108285, ECO:0000269|PubMed:26224785, ECO:0000269|PubMed:8939939}. Note=The disease is caused by mutations 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 ABL; no loss on localization to the endoplasmic reticulum; does not reduce interaction with APOB; inhibits interaction with P4HB/PDI; inhibits phospholipid or triglyceride transfer activity; inhibits apolipoprotein B secretion.
Any additional useful information about the variant.



Sequence information

Variant position:  169
The position of the amino-acid change on the UniProtKB canonical protein sequence.

Protein sequence length:  894
The length of the canonical sequence.

Location on the sequence:   KRGLASLFQTQLSSGTTNEV  D ISGNCKVTYQAHQDKVIKIK
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: 
The multiple alignment of the region surrounding the variant against various orthologous sequences.

Human                         KRGLASLFQTQLSSGTTNEVDISGNCKVTYQAHQDKVIKIK

Mouse                         KRGLASLFQMQLSSGTTNEVDISGDCKVTYQAQQDKVVKIK

Pig                           KRGLASLFQMQLSSGTTNEVDISGDCKVTYQAHQDKVTKIK

Zebrafish                     KRGVASMLMMQLKSGKMSEADASGKCLVEYKVNKHQVIRTK

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 19 – 894 Microsomal triglyceride transfer protein large subunit
Domain 28 – 659 Vitellogenin
Alternative sequence 152 – 894 Missing. In isoform 2.
Mutagenesis 169 – 169 D -> E. No loss on localization to the endoplasmic reticulum and does not reduce interaction with APOB or P4HB/PDI, does partially reduce phospholipid or triglyceride transfer activity and apolipoprotein B secretion.
Mutagenesis 187 – 187 K -> L. No loss on localization to the endoplasmic reticulum and does not reduce interaction with APOB, but inhibits interaction with P4HB/PDI, phospholipid or triglyceride transfer activity and apolipoprotein B secretion.
Mutagenesis 187 – 187 K -> R. No loss on localization to the endoplasmic reticulum, does not reduce interaction with APOB or P4HB/PDI, partially inhibits triglyceride transfer activity, does not inhibit phospholipid transfer activity and apolipoprotein B secretion.
Mutagenesis 189 – 189 K -> L. No loss on localization to the endoplasmic reticulum and does not reduce interaction with APOB, but inhibits interaction with P4HB/PDI, phospholipid or triglyceride transfer activity and apolipoprotein B secretion.
Mutagenesis 189 – 189 K -> R. No loss on localization to the endoplasmic reticulum, does not reduce interaction with APOB or P4HB/PDI, partially inhibits triglyceride transfer activity, does not inhibit phospholipid transfer activity and apolipoprotein B secretion.


Literature citations

A novel abetalipoproteinemia missense mutation highlights the importance of N-Terminal beta-barrel in microsomal triglyceride transfer protein function.
Walsh M.T.; Iqbal J.; Josekutty J.; Soh J.; Di Leo E.; Oezaydin E.; Guenduez M.; Tarugi P.; Hussain M.M.;
Circ. Cardiovasc. Genet. 8:677-687(2015)
Cited for: VARIANT ABL VAL-169; CHARACTERIZATION OF VARIANT ABL VAL-169; FUNCTION; INTERACTION WITH APOB AND P4HB; SUBCELLULAR LOCATION; MUTAGENESIS OF ASP-169; LYS-187 AND LYS-189;

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.