Objectives: To clone apolipoprotein AI (apoAI) gene from tree shrew (TS) which is an animal insusceptible to atherosclerosis and to analyze the characteristics of the gene.
Methods: A cDNA library of the liver tissue was constructed by using the isolated mRNA as the template during reverse transcription. The positive clones of apoAI cDNA were identified in the library with an anti-serum to TS apoAI. Sequencing, analyzing and expressing of the clones were finished.
Results: A complete cDNA sequence of TS apoAI was determined as 900 nucleotides. It contained 28 bp in 5' untranslated region, and 795 bp in an open reading frame encoding a 265-amino acid apoAI precursor (an 18-amino acid signal peptide, a 6-amino acid propeptide and a 241-amino acid mature protein), two stop codens (TGA, TAA) and following 72 bp in 3' untranslated region. The novel gene was submitted to GenBank. TS apoAI deduced from the cDNA sequence was more hydrophobic than that of human. The results of Northern blot indicated the plentiful presence of apoAI mRNA in TS liver and intestine.
Conclusions: A new gene was cloned from TS, one animal insusceptible to atherosclerosis. TS apoAI may have a stronger activity of binding cholesterol and cholesterol ester than that of human apoAI in reverse cholesterol transport. A good foundation was laid for studying the molecular structure and function of TS apoA I.