不同物种间胰岛素及其编码mRNA,DNA序列比较与分析

通过PSI-BLAST搜索与人类胰岛素原(含有86个氨基酸)相似的蛋白质序列，并进行比对，计算比对矩阵的相似得分和期望值，同时运用ClustalW算法对不同物种编码前胰岛素原mRNA及其翻译的蛋白质和DNA序列进行多重比对．结果发现，脊椎动物的胰岛素蛋白质一级结构(A链和B链)和mRNA非常相似，但部分动物C肽的部分序列有差异；系统进化分析表明，人和猴、小鼠和大鼠编码胰岛素的mRNA在进化上关系相近．各物种间编码相同氨基酸的核苷酸序列（CDS)相同，但编码胰岛素的DNA序列不同．各物种胰岛素原蛋白质序列中，A链和B链序列保守，C肽有一定的差异；DNA序列差异较大．

Comparison and analysis of insulin sequences and their coded mRNA and DNA among different species

In order to understand the sequences of insulin (protein), mRNA and DNA among different species, PSI BLAST was used to search for the similar protein sequences on the basis of human proinsulin (86 amino acids), and the sequences alignments were made. Meanwhile, the ClustalW program was utilized to make multiple sequences alignment of coding mRNA, translated preproinsulin, and DNA of insulin. The results indicate that the insulin(A chain and B chain) primary protein sequences and mRNA of vertebrate are quite similar. But C peptide of some animals show some differences in part of amino acid sequences. Analysis of phylogenetic tree indicates that human and monkey, mouse and rat are quite similar in the evolution. There are obvious differences between human insulin DNA sequences and those of mouse or rat. However, the CDS mRNA of varied species coding the same amino acids are homology. The conclusion is that insulin (A, B chains) sequences are conservative, however the sequences of C peptide have some difference among human and animals, while the DNA sequences have obvious difference in human, mouse and rat.