Characterization of a rat variant alpha-fetoprotein
T Watanabe1, J L Jimenez-Molina, J Y Chou
1Human Genetics Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
Biochemical and Biophysical Research Communications
|June 15, 1992
Summary
Researchers identified a novel variant alpha-fetoprotein (AFP) mRNA in adult rat liver. This variant transcript, ARFP9, is differentially regulated compared to the fetal AFP mRNA.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Adult rat liver and hepatocytes express a 1.7-kb variant alpha-fetoprotein (AFP) mRNA, distinct from the 2.2-kb fetal transcript.
- The variant mRNA differs in its 5' sequence compared to the fetal form.
Purpose of the Study:
- To characterize a variant AFP cDNA, designated ARFP9.
- To investigate the expression and regulation of the variant AFP transcript.
Main Methods:
- cDNA sequencing and characterization of ARFP9.
- In vitro expression studies.
- Analysis of gene regulation using Methyl-isobutyl-xanthine (MIX).
Main Results:
- ARFP9 is a 1349 bp cDNA encoding a 325 amino acid polypeptide.
- The variant transcript contains a unique 224-bp sequence from the 7th intron (V exon) not present in fetal AFP mRNA.
- In vitro expression yielded an unglycosylated 37 kDa intracellular protein.
- MIX stimulated fetal AFP mRNA but inhibited variant AFP mRNA expression.
Conclusions:
- A novel variant alpha-fetoprotein (AFP) mRNA (ARFP9) has been characterized in adult rat liver.
- The variant AFP transcript is developmentally and differentially regulated compared to the fetal form.
- These findings suggest distinct regulatory mechanisms for fetal and variant AFP transcripts in rats.
