Pre Initiation Complex

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The complexicity of PIC&nbsp;varies between the types of eukaryotic [[Rna polymerases in eukaryotes|RNA polymerase]]. For [[DNA polymerase I|polymerases I]]&nbsp;and [[Polymerase III|III]] the complex consists of only a few subunits.<br>  
 
The complexicity of PIC&nbsp;varies between the types of eukaryotic [[Rna polymerases in eukaryotes|RNA polymerase]]. For [[DNA polymerase I|polymerases I]]&nbsp;and [[Polymerase III|III]] the complex consists of only a few subunits.<br>  
  
For [[RNA_polymerase_II|polymerase II]] the PIC&nbsp;is far more complex. It consists of 6 [[General Transcription Factors|General Transcription Factors]] (GTF). [[TFIID|TFIID]] is the core recognition [[Protein|protein]] and binds to the [[Tata box|TATA&nbsp;box]]. [[TFIIA |TFIIA]] stabilizes the binding complex. TFIID&nbsp;intreacts with TFIIB&nbsp;which brings in the [[RNA_polymerase_II|RNA&nbsp;polymerase II]]&nbsp;which has [[TFIIF|TFIIF]] attached to it. This allows [[TFIIE|TFIIE]]&nbsp;and finally [[TFIIH|TFIIH]]&nbsp;to bind. TFIIH has [[Helicase|helicase]] activity and starts seperating the strands at the [[Open complex|Open Complex]]. Further it has CTD&nbsp;[[Kinase|Kinase activity]] and facilitates [[DNA]] repair. <br>  
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For [[RNA polymerase II|polymerase II]] the PIC&nbsp;is far more complex. It consists of 6 [[General Transcription Factors|General Transcription Factors]] (GTF). [[TFIID|TFIID]] is the core recognition [[Protein|protein]] and binds to the [[Tata box|TATA&nbsp;box]]. [[TFIIA|TFIIA]] stabilizes the binding complex. TFIID&nbsp;intreacts with TFIIB&nbsp;which brings in the [[RNA polymerase II|RNA&nbsp;polymerase II]]&nbsp;which has [[TFIIF|TFIIF]] attached to it. This allows [[TFIIE|TFIIE]]&nbsp;and finally [[TFIIH|TFIIH]]&nbsp;to bind. TFIIH has [[Helicase|helicase]] activity and starts seperating the strands at the [[Open complex|Open Complex]], this process requires [[ATP_hydrolysis|ATP-hydrolysis]]. Further it has CTD&nbsp;[[Kinase|Kinase activity]] and facilitates [[DNA]] repair. <br>  
  
 
=== References  ===
 
=== References  ===

Revision as of 18:51, 22 October 2018

In eukaryotic gene expression the Pre Initiation Complex (PIC) mediates the binding between the genome's promoter and RNA polymerase. Each type of RNA polymerase has a different PIC [1].

Subunits

The complexicity of PIC varies between the types of eukaryotic RNA polymerase. For polymerases I and III the complex consists of only a few subunits.

For polymerase II the PIC is far more complex. It consists of 6 General Transcription Factors (GTF). TFIID is the core recognition protein and binds to the TATA box. TFIIA stabilizes the binding complex. TFIID intreacts with TFIIB which brings in the RNA polymerase II which has TFIIF attached to it. This allows TFIIE and finally TFIIH to bind. TFIIH has helicase activity and starts seperating the strands at the Open Complex, this process requires ATP-hydrolysis. Further it has CTD Kinase activity and facilitates DNA repair.

References

  1. Cassimeris,L. et al., 2007; p219 Lewin's cells. 2nd ed. Sudbury: Jones and Bartlett.


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