加载中…反义RNA，S-D序列（Shine-Dalgarno sequence）
(2013-01-24 21:47:01)
标签：
杂谈 |
分类： 核酸 |
|
定义： 反义RNA是指与mRNA互补的RNA分子，也包括与其它RNA互补的RNA分子。由于核糖体不能翻译双链的RNA，所以反义RNA与mRNA特异性的互补结合, 即抑制了该mRNA的翻译。通过反义RNA控制mRNA的翻译是原核生物基因表达调控的一种方式，最早是在E.coli 的产肠杆菌素的Col E1质粒中发现的，许多实验证明在真核生物中也存在反义RNA。近几年来通过人工合成反义RNA的基因, 并将其导入细胞内转录成反义RNA，即能抑制某特定基因的表达，阻断该基因的功能，有助于了解该基因对细胞生长和分化的作用。同时也暗示了该方法对肿瘤实施基因治疗的可能性 |
分类：
|
Shine-Dalgarno sequenceThe Shine-Dalgarno sequence (AGGAGG), proposed by
Australian scientists John Shine and Lynn Dalgarno,[1] is a
ribosomal binding site located upstream of the start codon AUG. It
is a consensus sequence that helps recruit the ribosome to the mRNA
to initiate protein synthesis by aligning it with the start codon.
The complementary sequence (CCUCCU), is called the
anti-Shine-Dalgarno sequence and is located at the 3' end of the
16S rRNA in the ribosome.
Mutations in the Shine-Dalgarno sequence can
reduce translation. This reduction is due to a reduced
mRNA-ribosome pairing efficiency, as evidenced by the fact that
complementary mutations in the anti-Shine-Dalgarno sequence can
restore translation.
When the Shine-Dalgarno sequence and the
anti-Shine-Dalgarno sequence pair, the translation initiation
factors IF2-GTP, IF1, IF3, as well as the initiator tRNA
fMet-tRNA(fMET) are recruited to the ribosome.
Shine-Dalgarno sequence vs. ribosomal S1
protein
In Gram-negative bacteria, however,
Shine-Dalgarno sequence presence is not obligatory for ribosome to
locate initiator codon, since deletion of Anti-Shine-Dalgarno
sequence from 16S rRNA doesn't lead to translation initiation at
non-authentic sites. Moreover, numerous prokaryotic mRNAs don't
possess Shine-Dalgarno sequences at all. What principally attracts
ribosome to mRNA initiation region is apparently ribosomal protein
S1, which binds to AU-rich sequences found in many prokaryotic
mRNAs 15-30 nucleotides upstream of start-codon. It should be
noted, that S1 is only present in Gram-negative bacteria, being
absent from Gram-positive species
|
喜欢
0
赠金笔
前一篇：[转载]简介
后一篇：R字符串处理（转载）