牦牛KAP6-1和KAP6-4基因序列变异分析

Sequence Variation Analysis of KAP6-1 and KAP6-4 Genes in Yak

角蛋白关联蛋白（keratin-associated proteins,KAPs）是毛纤维的主要结构成分。以甘南牦牛、青海牦牛、天祝白牦牛和野血牦牛为研究对象,应用PCR-SSCP方法检测KAP6-1和KAP6-4基因外显子序列多态性。结果表明4个牦牛群体的KAP6-1基因外显子区存在c.42T〉C、c.135C〉T的同义突变及c.173G〉C、c.175G〉T的非同义突变,导致p.Cys58Ser和p.Gly59Cys的氨基酸残基改变;另外检测到1处45 bp的插入/缺失突变导致16个氨基酸残基的插入/缺失;甘南牦牛PIC值0.222 3为低度多态,其他3个牦牛群体PIC值0.393 4~0.4672为中度多态。牦牛KAP6-4基因外显子区检测到c.51C〉T、c.54C〉A、c.78T〉C、c.96T〉C和c.135T〉C的同义突变,以及c.118A〉G的非同义突变,导致编码的氨基酸残基p.Ser40Gly的改变;4类群牦牛PIC值为0.2658~0.387 2为中度多态。聚类分析表明牦牛KAP6-1基因外显子区碱基序列与普通牛、绵羊和山羊的同源性最高,其亲缘关系和系统进化远近一致。

Keratin-associated proteins（KAPs） are main structural components of wool fiber. In this study, Gannan yak, Qinghai yak, Tianzhu white yak and Wild-blood yak were selected as research objects, and the gene exons sequence polymorphism of KAP6-1 and KAP6-4 was tested by PCR-SSCP. The results showed that KAP6-1 gene exon regions in 4 yak groups were detected to contain two synonymous mutations（c.42 T〉C and c.135 C〉T） and two nonsynonymous mutation（c.173 G〉C and c.175 G〉T）, which led to the change of amino acid residues in p.Cys58 Ser and p.Gly59 Cys. A 45-bp insertion/deletion mutation led to 16 amino-acid residue iznsertion/deletion. The 3 yak populations presented moderate polymorphism with PIC value in range of 0.393 4~0.467 2 except Gannan yak with low polymorphism as PIC=0.222 3. Yak KAP6-4 gene exon regions were identified to include five synonymous mutations（c.51 C〉T, c.54 C〉A, c.78 T〉C, c.96 T〉C and c.135 T〉C） and one nonsynonymous mutation（c.118 A〉G）,which led to the change of amino acid residues in p.Ser40 Gly. The 4 yak populations showed moderate polymorphism with PIC value in range of 0.265 8~0.387 2. The cluster anazzlysis indicated that KAP6-1 gene exon base sequence of yak was the most homologous with that of cattle, sheep and goat, and its genetic relationship and phylogenetic distancewere close to each other.