山羊CAST基因Ⅱ型转录本的克隆及在山羊不同组织中的表达

Cloning and tissue expression of CAST transcriptⅡ in goat

钙蛋白酶抑制蛋白（Calpastatin，CAST）基因是与畜禽肉质性状密切相关的重要候选基因。文章根据牛和绵羊CAST基因mRNA，应用RACE技术首次成功克隆了山羊CAST基因Ⅱ型转录本（以下简称CASTII基因）全长cDNA，对序列及编码的氨基酸进行了生物信息学分析。结果显示，该基因cDNA全长2474bp，完整的开放阅读框（ORF）为558～2252bp，编码564个氨基酸。氨基酸序列中存在4个保守结构域和1个保守七肽序列；蛋白质二级结构以无规卷曲和a-螺旋为主，富含疏水区，存在多个磷酸化位点以及蛋白激酶C（Protein kinaseC，PKC）的磷酸化位点。通过实时荧光定量RT—PCR技术分析了CASTⅡ基因在天府肉羊部分组织中的表达情况。结果表明：CASTII基因在所选择的天府肉羊7种组织中均有表达，半岁各组织中，眼肌的表达量最高，与腿肌差异显著（P〈0．05），极显著高于内脏各组织（P〈0．01）；在眼肌组织中，CASTⅡ基因的表达量随着年龄的增长而增加，3岁时的表达量最高。

Calpastatin （CAST） gene is closely related with meat quality in livestock and poultry. Based on the bovine and ovine mRNA sequences, the cDNA of CAST 1I gene in goat was amplified successfully for the first time by using RACE-PCR. Results showed that CASTII of goat was 2474 bp in length with an open reading frame （ORF） 1695 bp long and encoded 564 amino acids, and there were four conserved domains and one conserved seven-peptide domain in amino acids sequences. Bioinformation analysis indicated that its secondary structures mainly were random coil and helical re- gions, and contained rich hydrophobic regions, certain phosphorylation sites, and protein kinase C （PKC） sites. Meanwhile, analysis of tissue expression of the gene in Tianfu meat goat demonstrated it was expressed in seven selected tissues. When the goat was of 6-month age, the highest expression was observed in longissimusdorsi, which was significantly higher than that of erureus （P〈0.05） and other internal organ tissues （P〈0.01）.[0] Furthermore, the expression of CAST II increasedwith the rise of the age and became the highest when the goat was at three-year age.