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UniProtKB/Swiss-Prot variant pages

UniProtKB/Swiss-Prot P55157: Variant p.Asp169Val

Microsomal triglyceride transfer protein large subunit
Gene: MTTP
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Variant information Variant position: help 169 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 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: help 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: 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 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: help 169 The position of the amino-acid change on the UniProtKB canonical protein sequence.
Protein sequence length: help 894 The length of the canonical sequence.
Location on the sequence: help 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: help The multiple alignment of the region surrounding the variant against various orthologous sequences. 
Human                         KRGLASLFQTQLSSGTTNEVDIS---GNCKVTYQAHQDKVIKIK

Mouse                         KRGLASLFQMQLSSGTTNEVDIS---GDCKVTYQAQQDKVV

Rat                           KRGLASLFQMQLTSGTTNEVDIS---GDCKVTYQAQQDKVV

Pig                           KRGLASLFQMQLSSGTTNEVDIS---GDCKVTYQAHQDKVT

Zebrafish                     KRGVASMLMMQLKSGKMSEADAS---GKCLVEYKVNKHQVI

Caenorhabditis elegans        LYAIVNTIYTPAEYGEGDEQTVDTIYGRCFVNFGRPEDKRF

Drosophila                    ERGIASLLQLRLDASQEEELDVS---GLCRVSYNVKSSTKV
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 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.
Beta strand 169 – 171



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.