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lsss

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[交流] 【求助/交流】外显子和内含子？？已有8人参与

用NCBI的SPLIGN分析牛ACACA基因，结果发现其有56个外显子，其CDS为341-7381。即图中显示，其编码启始位点在第三个外显子内，难道其第一、第二外显子都在UTR区？那还叫外显子吗?很困惑，请各位虫友指点，多谢！！！

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1楼 2010-07-30 14:49:27

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看天(金币+4):求助者助人大家互助分享这是一种值得鼓励的精神 2010-08-02 17:42:27

感谢楼上两位兄弟的解释，我又在维基百科搜索了外显子的含义，这回算是弄明白了，下面是一部份解释，贴出来共享：
In many genes, each exon contains part of the open reading frame (ORF) that codes for a specific portion of the complete protein. However, the term exon is often misused to refer only to coding sequences for the final protein. This is incorrect, since many noncoding exons are known in human genes (Zhang 1998).

To the right is a diagram of a heterogeneous nuclear RNA (hnRNA), which is an unedited mRNA transcript, or pre-mRNAs. Exons can include both sequences that code for amino acids (red) and untranslated sequences (grey). Stretches of unused sequence called introns (blue) are removed, and the exons are joined together to form the final functional mRNA. The notation 5' and 3' refer to the direction of the DNA template in the chromosome and is used to distinguish between the two untranslated regions (grey).

Some of the exons will be wholly or part of the 5' untranslated region (5' UTR) or the 3' untranslated region (3' UTR) of each transcript. The untranslated regions are important for efficient translation of the transcript and for controlling the rate of translation and half life of the transcript. Furthermore, transcripts made from the same gene may not have the same exon structure since parts of the mRNA could be removed by the process of alternative splicing. Some mRNA transcripts have exons with no ORF's and thus are sometimes referred to as non-coding RNA.

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9楼2010-08-02 10:37:43

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fppzcz

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小木虫(金币+0.5):给个红包，谢谢回帖交流
1949stone(金币+2):学习交流 2010-07-30 15:30:48

不明白，但是个人感觉1.2应该属于前导肽类似的功能，
　UTR（Untranslated Regions)即非翻译区，是mRNA分子两端的非编码片段。
　　5'-UTR从mRNA起点的甲基化鸟嘌呤核苷酸帽延伸至AUG起始密码子，3'-UTR从编码区末端的终止密码子延伸至多聚A尾巴（Poly-A）的末端。

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2楼2010-07-30 15:10:05

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