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Human alpha-tocopherol transfer protein: cDNA cloning, expression and chromosomal localization
1Department of Health Chemistry, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
The Biochemical Journal
|March 1, 1995
Summary
Researchers identified human alpha-Tocopherol transfer protein (alpha TTP) in liver cells, crucial for vitamin E transport. This protein shares similarities with rat alpha TTP and is linked to a genetic disorder affecting vitamin E levels.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Alpha-Tocopherol transfer protein (alpha TTP) facilitates vitamin E transfer between membranes.
- Previous studies isolated alpha TTP from rat liver cytosol.
Purpose of the Study:
- To demonstrate the presence and characteristics of alpha TTP in human liver.
- To investigate the genetic location and potential relation to clinical disorders.
Main Methods:
- Isolated human alpha TTP cDNA from a human liver library.
- Expressed recombinant human alpha TTP in E. coli for activity assays.
- Utilized Northern blot, Southern-blot hybridization, and fluorescence in situ hybridization for gene analysis.
Main Results:
- Human alpha TTP cDNA predicts 278 amino acids with 94% similarity to rat alpha TTP.
- Recombinant human alpha TTP showed vitamin E transfer activity and cross-reacted with anti-rat alpha TTP antibody.
- The human alpha TTP gene is located on chromosome 8q13.1-13.3, coinciding with the locus for ataxia with selective vitamin E deficiency (AVED).
Conclusions:
- Human alpha TTP is present in the liver and shares structural and functional similarities with its rat counterpart.
- The genetic locus of human alpha TTP is strongly associated with AVED, suggesting a direct link between the protein and the disorder.