摘要
真核细胞mRNA前体经过剪接成为成熟的mRNA ,而mRNA前体的选择性剪接极大地增加了蛋白质的多样性和基因表达的复杂程度 ,剪接位点的识别可以以跨越内含子的机制 (内含子限定 )或跨越外显子的机制 (外显子限定 )进行。选择性剪接有多种剪接形式 :选择不同的剪接位点 ,选择不同的剪接末端 ,外显子的不同组合及内含子的剪接与否等。选择性剪接过程受到许多顺式元件和反式因子的调控 ,并与基本剪接过程紧密联系 ,剪接体中的一些剪接因子也参与了对选择性剪接的调控。选择性剪接也是 1个伴随转录发生的过程 ,不同的启动子可调控产生不同的剪接产物。mRNA的选择性剪接机制多种多样 ,已发现RNA编辑和反式剪接也可参与选择性剪接过程。
Eukayotic pre-mRNAs are spliced to form mature mRNA.The pre-mRNAs alternative splicing greatly increases the diversity of proteins and the complexity of genes expression.The recognition of splice sites can occur across intron (intron definition) or across exon (exon definition).There are many kinds of alternative splicing patterns,including the choice of alternative splicing sites,the choice of alternative splicing ends,the alternative splicing of mutually exclusive exons,and an intron can be excised from or retained in mRNA.The splice sites choice process is regulated by many kinds of cis-acting and trans-acting elements and is closely related with the basic splicing process.Some of the splicing factors in basic splicing process can regulate the alternative splicing.The alternative splicing is also a co-transcriptional process.Promoters can regulate alternative splicing and produce different mRNA isoforms.Many molecular mechanisms of alternative splicing have been proposed,and it was also found that the RNA editing and trans-splicing could also regulate alternative splicing.
