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可变剪接是基因表达调控的一种重要方式。本研究利用RT-PCR克隆鉴定到草菇exo-β-1,3-葡聚糖酶基因(exg2)的4种可变剪接体(exg2V1,exg2V2,exg2V3和exg2V4),其中,exg2V1第7个内含子保留;exg2V2第11个内含子保留同时剪切掉第12个外显子的后58bp;exg2V3同时保留第7个和第17个内含子;exg2V4同时保留第2、第9和第17个内含子。4种剪接体均在可变剪接位点提前出现终止密码子,导致预测编码的氨基酸序列中包含不完整的结构域。定量PCR结果显示:草菇5个发育时期中,4种可变剪接体表达量均比标准剪接体exg2低,但4种可变剪接体的表达也表现出一定的时期和组织差异性。初步推断发现的草菇exg2基因4种可变剪接体均为无义介导的mRNA降解,通过此方式达到对exg2基因标准剪接转录本的精准调控。
Alternative splicing is an important way of regulating gene expression. In this study, four kinds of alternative splicing (exg2V1, exg2V2, exg2V3 and exg2V4) were identified by RT-PCR to the exo-β-1,3-glucanase gene (exg2) Intron; exg2V2 eleventh intron retains the second exon at the same time after cutting off 58bp; exg2V3 while retaining the seventh and the 17th intron; exg2V4 while retaining the 2nd, 9th and The 17th intron. All four spliceosomes appeared premature stop codons at alternative splice sites, resulting in the predicted encoded amino acid sequence containing an incomplete domain. Quantitative PCR results showed that among the four developmental stages, the expression levels of four alternative splicing constructs were lower than that of standard splicing exg2, but the expression of four alternative splicing constructs also showed a certain period and tissue difference. Preliminary inference found that the four kinds of exg2 genetically modified spliced shrews are nonsense-mediated mRNA degradation, by this way to achieve exg2 standard splicing transcript precise regulation.