西农萨能羊凝乳酶原前体cDNA的克隆与序列分析

参照GenBank登录的绵羊凝乳酶原前体cDNA序列设计引物,以新生5d的西农萨能羊皱胃组织总RNA为模版,通过RT-PCR方法获得凝乳酶原前体cDNA,克隆测序后进行序列比对。结果表明,克隆基因为B型凝乳酶,该基因cDNA具有1292个碱基,编码381个氨基酸,包含16个氨基酸的信号肽序列和42个氨基酸的酶原序列。将其与已报道的山羊、绵羊和牛的凝乳酶原前体序列进行比对,发现核苷酸同源性分别为99.41%、98.74%和95.29%,氨基酸同源性为99.21%、98.42%和93.70%。

Cloning and sequence analyses of preprochymosin cDNA of Xinong Saanen Goat

Two pairs of primers were designed based on the sequence of ovis aries preprochymosin cDNA reported in GenBank.The preprochymosin cDNA was obtained from toltal RNA isolated from the abomasum of 5-day-old Xinong Saanen Goat by RT-PCR method and then cloned successfully in E.coli.The sequencing results indicated that the cDNA gene coded for chymosin B and had 1 292 nt which coded 381 amino acid residues.The sequence of amino acids included a predicted signal peptide region(16 amino acids) and a prochymosin region(42 amino acids).Comparison of the Xinong Saanen Goat preprochymosin sequence with those of the goat,sheep and cattle revealed 99.41%,98.74%,95.29% and 99.21%,98.42%,94.22% identity at the nucleotide and amino acid level,respectively.