【摘要】 以从树肝脏mRNA反转录获得的cDNA一链为模板 ,应用SMART RACE技术 ,获得了树apoCⅡ的cDNA序列 ,并推导出其蛋白质氨基酸序列 ,应用分子生物学软件对该蛋白的一级、二级结构进行分析和比较。结果显示 ,树apoCⅡcDNA序列 (在GenBank中的注册号为AF335 5 85 )长 483bp ,其中开放阅读框架 30 6bp ,编码 10 1个氨基酸的前原蛋白 ,其蛋白原由 79个氨基酸组成。树apoCⅡ的氨基酸顺序与人、猴、狗的同源性分别为 86 %、87%和 81%。与人及其它种属动物的相同序列比较显示 ,树apoCⅡ分子C 端激活LPL功能区比N 端脂质结合区更具保守性。更多还原

【Abstract】 The sequence of apolipoproteinCⅡ cDNA from tree shrew, a good model for its insusceptibility to atherosclerosis, was identified by SMART (Switching Mechanism At 5’ end of RNA Transcript) and RACE (Rapid Amplification of cDNA End) from the first strand of cDNA. The amino acid sequence of apolipoproteinCⅡ was deduced from this cDNA and its primary and secondary structures were predicted by "DNAMAN", the software for molecular biology. The results showed that tree shrew apolipoproteinCⅡ cDNA sequence covered 483 bp, including a 306 bp fragment in an open reading frame (ORF) and 177bp at 3’ of the untranslated region. The stop codon is TAG and the poly(A) signal is AATAAA that precedes 3’ poly(A) tail by 8 nucleotides. The ORF encodes 101 amino acids (aa) pre-proapolipoproteinCⅡ, which contains a hydrophobic signal peptide of 22 amino acids and a proapolipoproteinCⅡ of 79 amino acids. Tree shrew apoCⅡ is lack of Cys and His while rich in hydrophobic amino acids such as Leu and Ala. Comparing this amino acid sequence with those of other animals, it reveals that tree shrew apoCⅡ shared the same length with that of human, monkey and dog. The homology among tree shrew and human, monkey, dog, pig, rat apoCⅡ is 86%, 87%, 81%, 76% and 76% at protein level respectively. The conservation is high in the C-terminal part of apoCⅡ molecules, while there are more substitutions in the N-terminal portion. The sequence of apoCⅡ cDNA from tree shrew was accepted by GenBank with the accession number of AF335585.更多还原