陇东绒山羊KRTAP2-1基因鉴定及其对羊绒性状影响的研究

角蛋白关联蛋白(KAPs)是羊绒纤维的主要结构成分,但尚未在山羊基因组中鉴定出KRTAP2-1基因,本研究以人类KRTAP2-1基因为模板,在山羊基因组中进行同源性搜索,在19号染色体上发现了一个399 bp的开放阅读框。采用聚合酶链反应-单链构象多态性(PCR-SSCP)方法,在249只陇东山羊上检测到7条不同的序列(A-G)。进化树结果表明,这7条序列与人类和绵羊的KAP2-1序列有较高的同源性,表明该序列是山羊KRTAP2-1的7个等位基因。测序结果表明,KRTAP2-1基因中存在12个单核苷酸多态性(SNPs)(5个SNPs位于编码区,7个SNPs位于非编码区),以及c.-61_-63delCTC和c.93_95delCCG两个碱基缺失,其中c.93_95delCCG引起了第32位精氨酸的移码缺失。山羊KAP2-1蛋白含有丰富的半胱氨酸、脯氨酸、苏氨酸和丝氨酸。相关性分析表明,等位基因C的存在与较小的羊绒纤维直径相关(存在:13.4±0.05 μm;缺失:13.6±0.03 μm;P=0.010)。本研究表明,山羊KRTAP2-1基因有丰富的多态性,可作为陇东绒山羊羊绒纤维直径选育的分子标记用于生产实践。

Identification of the Caprine KRTAP2-1 Gene and Its Effect on Longdong Cashmere Traits

Keratin-associated proteins (KAPs) are main structural components of cashmere fibres, while KRTAP2-1 has not been identified in goat genome. In the study, a 399 bp open reading frame on chromosome 19 of goat was found to be homologous to human KRTAP2-1 sequences. Seven unique sequences (A-G) were detected in 249 Longdong cashmere goats using polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) analysis. These sequences have the highest homology with KAP2-1 sequences of human and sheep, suggesting that these are variants of caprine KRTAP2-1. Twelve single nucleotide polymorphisms (SNPs) and two insertion/deletion (c.-61_-63delCTC and c.93_95delCCG) were found within the gene, including five SNPs in the coding region and 7 SNPs in the non-coding region. c.93_95delCCG would result in a deletion of Arg at position 32. Caprine KAP2-1 contains high levels of cysteine, proline, threonine and serine. The presence of variant C was associated with the decrease in diameter of cashmere fibre(presence: 13.4 ± 0.05 μm, absence: 13.6 ± 0.03 μm, P=0.010). These results indicate that caprine KRTAP2-1 are polymorphic, and variations in caprine KRTAP2-1 are valuable to be a genetic marker for reducing cashmere fibre diameter in Longdong cashmere goats.