徹底搞清楚promoter, exon, intron, and UTR (有圖有真相)

1、徹底搞清楚promoter, exon, intron, and UTR啟動(dòng)子: RNA聚合酶特異性識(shí)別和結(jié)合的DNA序列。promoter自然不屬于intron和Exon的任何一個(gè)，屬于noncoding sequence。noncoding RNA是現(xiàn)在研究的熱點(diǎn)之一。我們常見的MiRNA,SiRNA, antisense RNA tech,這些都是屬于ncRNA的范圍。只要你在進(jìn)一步問下：這些RNA是哪里來的？你就知道部分答案，跟那些看似跟編碼蛋白沒有關(guān)系的DNA序列有關(guān)系。這部分DNA有個(gè)統(tǒng)稱就junk DNA，垃圾或者冗余DNA，他們編碼的RNA就屬于 ncRNA.RNAi就是迄今最

2、經(jīng)典的ncRNA功能典范。An exon is a sequence of DNA that is expressed (transcribed) into RNA and then often, but with many noteworthy exceptions1 , translated into protein. Adjacent exons may be separated by an intron, which is later removed from the RNA transcript via the splicing mechanism. (From Wikipedia)

3、UTR（Untranslated Regions)即非翻譯區(qū)，是信使RNA（mRNA）分子兩端的非編碼片段。 5-UTR從mRNA起點(diǎn)的甲基化鳥嘌呤核苷酸帽延伸至AUG起始密碼子，3-UTR從編碼區(qū)末端的終止密碼子延伸至多聚A尾巴（Poly-A）的末端。轉(zhuǎn)錄（Transcription）是遺傳信息從DNA到 RNA的轉(zhuǎn)移。即以雙鏈DNA中的一條鏈為模板，以ATP、CTP、GTP和UTP4種核苷三磷酸為原料，在RNA聚合酶催化下合成RNA的過程。PromotergeneCDSDNA：Pre mRNA：CDSCDSMature mRNA：CDSCDSCDSPoly AXXXXXXAUGXXXX.U

4、GAXXXXXXXXXXAAUAAAAAAAAAAstart codon: AUGstop codons ：UGA, UAG, UAA5UTR 3UTR PolyA ATGXXXXXXXXX.XXXXXXXTGAORF(open reading frame ) cDNA：TSS: transcription start site CDS(Coding sequence)PolyA是后來加上去的。Gene里沒有cDNA中有。5UTR3UTR3UTR5UTRcapIntron 1Exon 1Exon 2Intron 2Exon 3Gray area: 5UTR (1-45)TSS: transcr

5、iption start site Green area: intronIntron1 (73-1216)CDS (46-72)Start codon: ATG5UTR3UTRExon1Intron1Example1IL17A interleukin 17AHomo sapiensLocation : 6p12Sequence : Chromosome: 6; NC_000006.11 (52051185.52055436)gene 1.4252mRNA join(1.72,1217.1419,2669.4252)CDS join(46.72,1217.1419,2669.2906)Exon2

6、Intron2Exon3Example1IL17A interleukin 17AHomo sapiensLocation : 6p12Sequence : Chromosome: 6; NC_000006.11 (52051185.52055436)gene 1.4252mRNA join(1.72,1217.1419,2669.4252)CDS join(46.72,1217.1419,2669.2906)Gray area: 3UTR (2907-4252)Green area: intronIntron2 (1420-2668)CDS (2669-4252)End codon: TAA

7、Example2: Cx3cr1 chemokine (C-X3-C) receptor 1 Mus musculus Location : 9 F4; 9Sequence : Chromosome: 9; NC_000075.6 (120048693.120068282, complement)gene 1.19590mRNA join(1.78,15940.19590)CDS 15949.17013Gray area: 5UTR (15940-15948) in exon2Green area: Intron1(79-15939) CDS (15949-17013)Start codon: ATGEnd codon: TGA5UTR3UTRExon1Intron1互補(bǔ)鏈上Gray area: 3UTR (17014-19590) in exon2Exon2常見問題：問：Promoter在DNA序列中是算內(nèi)含子還是外顯子？ 答：都不是。屬于noncoding sequence。問：UTR在DNA序列中是算內(nèi)含子還是外顯子？ 答：外顯子。問：起始密碼子ATG在gene的哪個(gè)