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Human fatty acid synthase: properties and molecular cloning
A Jayakumar1, M H Tai, W Y Huang
1Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030, USA.
Summary
Researchers purified human fatty acid synthase (FAS) from HepG2 cells, revealing lower activity due to reduced 4'-phosphopantetheine. They also cloned the human brain FAS cDNA, providing insights into its structure and tissue expression.
Area of Science:
- Biochemistry
- Molecular Biology
- Human Genetics
Background:
- Fatty acid synthase (FAS) is a crucial enzyme in lipogenesis.
- Understanding human FAS is vital for metabolic research and disease understanding.
Purpose of the Study:
- To purify and characterize human fatty acid synthase (FAS) from the HepG2 cell line.
- To clone and analyze the human brain FAS cDNA sequence.
- To investigate the expression patterns of human FAS mRNA in various tissues.
Main Methods:
- Purification of FAS from HepG2 cells.
- Cloning of human brain FAS cDNA.
- Nucleotide sequencing and Northern blot analysis.
Main Results:
- HepG2 FAS exhibited approximately half the specific activity of chicken liver FAS.
- Lower beta-ketoacyl synthase activity in HepG2 FAS was linked to reduced 4 -phosphopantetheine content.
- Human FAS cDNA encodes a 2504-amino acid protein with high identity to rat and chicken FAS.
- Human FAS mRNA (9.3 kb) showed prominent expression in brain, lung, and liver tissues.
- A sequence variance in HepG2 FAS cDNA was identified but did not explain the reduced enzyme activity.
Conclusions:
- Human FAS from HepG2 cells has distinct characteristics, particularly in its beta-ketoacyl synthase activity.
- The cloned human brain FAS cDNA provides a valuable resource for studying FAS structure-function relationships.
- Tissue-specific expression of human FAS suggests differential roles in various organs.