Andersson Y, Nilsson S, Lindberg A, Thelander L, Olivecrona G
Department of Medical Biochemistry and Biophysics, Umeâ University, S-901 87 Umeâ, Sweden.
J Biol Chem. 1996 Dec 20;271(51):33060-6. doi: 10.1074/jbc.271.51.33060.
The amino acid sequence of chicken apolipoprotein CII (apoCII) was determined from cDNA sequencing and from partial protein sequencing. The chicken sequence showed an overall identity of around 30% to all the other previously known apoCII sequences. Comparison of the carboxyl-terminal domain (residues 51-79, human numbering) showed at least 50% identity between species. By limiting the region to residues 51-70 the similarity was remarkably high, about 85%. This is in concert with the previous opinion that residues in the region 56-76 are directly engaged in binding to lipoprotein lipase and in activation of this enzyme. In contrast, in the amino-terminal end up to residue 50 (human numbering) less than 24% of the amino acid residues in chicken apoCII were identical to residues of any of the other species. In addition, chicken apoCII is four residues longer than human apoCII (83 versus 79 residues), probably due to an extension at the amino-terminal end. Although the sequence was completely different in the amino-terminal domain, the structures necessary for binding to lipid appear to be present in chicken apoCII. Secondary structure prediction showed that the amino-terminal domain could form two amphipathic alpha-helices in almost similar areas of the sequence as was previously predicted for human apoCII.
通过cDNA测序和部分蛋白质测序确定了鸡载脂蛋白CII（apoCII）的氨基酸序列。鸡的序列与所有其他先前已知的apoCII序列的总体同一性约为30%。对羧基末端结构域（第51 - 79位残基，以人类编号）的比较显示，不同物种之间至少有50%的同一性。将区域限制在第51 - 70位残基时，相似性非常高，约为85%。这与之前的观点一致，即56 - 76区域的残基直接参与与脂蛋白脂肪酶的结合以及该酶的激活。相比之下，在氨基末端直至第50位残基（以人类编号），鸡apoCII中不到24%的氨基酸残基与其他任何物种的残基相同。此外，鸡apoCII比人类apoCII长四个残基（83个与79个残基），这可能是由于氨基末端的延伸。尽管氨基末端结构域的序列完全不同，但鸡apoCII中似乎存在与脂质结合所需的结构。二级结构预测表明，氨基末端结构域可以在序列中几乎与先前预测的人类apoCII相似的区域形成两个两亲性α-螺旋。
