PPT 37-42

RNA转录过程：真核生物RNA转录的起始，延长，和终止。

§2.2 真核生物RNA转录

真核转录主要特点：

★① RNA聚合酶：RNA pol in eukaryotes:Ⅰ ,Ⅱ, Ⅲ

★② RNA pol Ⅱ通过转录因子作用，间接结合启动子

★③ 多种顺式作用元件和多种蛋白因子参与

★④ 转录终止和转录后修饰加工相偶联.

Initiation(起始)

 ★Transcription factor II（TFII）: TFs which direct RNA pol II to promoter and help to initiate transcription.

•TBP: TATA box binding protein, one subunit of TFIID

TAFs:TBP associated proteins. 

                                                

·TFII D  binds TATA box

·TFIIAandTFII B join to form ternary complex—

·TFIIF binds RNA pol II and join thecomplex——

·The addition of TFII E and TFII F is the final step

·—TFIIH unwind DNA strands  and phosphates CTD

·RNApol II and TFIIs form preinitiationcomples (PIC)-转录前起始复合物,PIC is similar to RNA polholoenzymein prokaryote.— 

In vivo, Transcription Initiation Requires Additional Proteins

      Assembly of the pre-initiation complex in presence ofmediator, nucleosome modifiers and remodelers, and transcriptionalactivators.起始中需要更多的蛋白因子参与

—Elongation(延长)

—Termination(终止)