Operons in eukaryotes
Operons in eukaryotes
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DOI：
10.1093/bfgp/3.3.199
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发表时间：
2004-11-01
期刊：
影响因子：
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通讯作者：
Blumenthal, Thomas
中科院分区：
文献类型：
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作者：
Blumenthal, Thomas
多顺反子转录被认为是细菌和古细菌的特征，其中许多基因聚集在由两个到十个以上基因组成的操纵子中。相比之下，真核生物的基因通常被认为是单顺反子的，每个基因在5 '端有自己的启动子，在3'端有一个转录终止子;然而，最近已经清楚的是，并非所有的真核生物基因都是单顺反子转录的。从原生生物到脊索动物，在真核生物中有许多多顺反子转录的例子。这些可以分为两大类。双顺反子转录单位指定编码两个单独基因的信使RNA（mRNA），其被运输到细胞质并以该形式翻译。据推测，内部核糖体进入位点（IRES），或终止密码子后的某种形式的翻译再起始，负责允许下游基因的翻译。在另一种类型中，初始转录物通过3′端切割和反式剪接加工成单顺反子mRNA，该mRNA被运输到细胞质并被翻译。与细菌操纵子一样，真核生物操纵子通常导致功能相关蛋白的共表达。
It was thought that polycistronic transcription is a characteristic of bacteria and archaea, where many of the genes are clustered in operons composed of two to more than ten genes. By contrast, the genes of eukaryotes are generally considered to be monocistronic, each with its own promoter at the 5′ end and a transcription terminator at the 3′ end; however, it has recently become clear that not all eukaryotic genes are transcribed monocistronically. Numerous instances of polycistronic transcription in eukaryotes, from protists to chordates, have been reported. These can be divided into two broad types. Dicistronic transcription units specify a messenger RNA (mRNA) encoding two separate genes that is transported to the cytoplasm and translated in that form. Presumably, internal ribosome entry sites (IRES), or some form of translational re-initiation following the stop codon, are responsible for allowing translation of the downstream gene. In the other type, the initial transcript is processed by 3′ end cleavage andtrans-splicing to create monocistronic mRNAs that are transported to the cytoplasm and translated. Like bacterial operons, eukaryotic operons often result in co-expression of functionally related proteins.