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lsss

木虫 (正式写手)

121-水手

[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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昔日寒山问拾得曰:世间谤我、欺我、辱我、笑我、轻我、贱我、恶我、骗我、如何处治乎?拾得云:只是忍他、让他、由他、避他、耐他、敬他、不要理他、再待几年.
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lsss

木虫 (正式写手)

121-水手

谢谢回复,现在就是不知道这种情况是特例,还是普遍存在,坐等高手来指点~~~
昔日寒山问拾得曰:世间谤我、欺我、辱我、笑我、轻我、贱我、恶我、骗我、如何处治乎?拾得云:只是忍他、让他、由他、避他、耐他、敬他、不要理他、再待几年.
3楼2010-07-30 15:21:41
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lsss

木虫 (正式写手)

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顶上去,等高人~~~~~~~~~~~~~
昔日寒山问拾得曰:世间谤我、欺我、辱我、笑我、轻我、贱我、恶我、骗我、如何处治乎?拾得云:只是忍他、让他、由他、避他、耐他、敬他、不要理他、再待几年.
4楼2010-07-31 07:37:44
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lsss

木虫 (正式写手)

121-水手

引用回帖:
Originally posted by lixg at 2010-07-31 08:10:17:
非常普遍,外显子拼接形成成熟的mRNA,多数基因都有UTR,它们也是外显子拼接的产物,所以,你会发现mRNA的长度要大于CDS,只有CDS才编码蛋白,AUG以前的mRNA编码前导序列。

谢谢解答!但还是有个疑问,这个例子中的第一、第二外显子就应该是你所说的前导序列,可它们通常是不翻译的,那这种处于UTR区的“外显子"还应该叫外显子吗?应该叫什么呢?NCBI给出的TXT格式的结论中也把它们成为exon,我所理解外显子就应该是编码蛋白的啊,很困惑~~~恳请帮忙~~~多谢~~~
昔日寒山问拾得曰:世间谤我、欺我、辱我、笑我、轻我、贱我、恶我、骗我、如何处治乎?拾得云:只是忍他、让他、由他、避他、耐他、敬他、不要理他、再待几年.
6楼2010-08-01 19:52:28
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lsss

木虫 (正式写手)

121-水手

★ ★ ★ ★
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.


昔日寒山问拾得曰:世间谤我、欺我、辱我、笑我、轻我、贱我、恶我、骗我、如何处治乎?拾得云:只是忍他、让他、由他、避他、耐他、敬他、不要理他、再待几年.
9楼2010-08-02 10:37:43
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