CAS BI 203 Lecture Notes - Lecture 12: Rna Polymerase Iii, Tata Box, Transcription Preinitiation Complex
22 May 2018
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Transcription Factors
Basic Transcription in Eukaryotes
- Identified using In vitro systems ID’d 5 General TFs (TFIIx) (ALL REQUIRED FOR
TRANSCRIPTION TO OCCUR):
- TFIID: TBP (TATA-binding protein) - binds TATA box (In pro and euk)
TAFs (TBP-associated factors) - bind other elements (lnr, DCE, etc.)
Identifying the place to bind in general
- TFIIB and TFIIF → Recruit RNA pol II to the site
- Has a Carboxyl-terminal tail
- TFIIE
TFIIH → Two Roles: 1) helicase 2) CTD kinase
help the preinitiation complex to start the transcription
- TFIID is made up of TATA-binding protein (TBP) - binds TATA box and
- TAFs (TBP-associated factors) - bind other elements (lnr, DCE, etc.)
- TFIIB and TFIIF → Recruitment of RNA pol II
- TFIIE
- TFIIH → Two Roles: 1) helicase 2) CTD kinase
- In the CTD (carboxy-terminal domain), you have
Tyr-Ser-Pro-Thr-Ser-Pro-Ser. It has 52 repeats in human (the serine in
the 5th position phosphorylates and that starts the transcription) So no
phosphorylation, no transcription (Phosphorylation of CTD is the GO)
- Additional factors contribute to transcription initiation within cells
- E.g. Mediator facilitates interactions between RNA pol II and regulator factors. It
mediates RNA pol II. Complex that holds everything together until it starts.
Mediator can speed up and slow down other things in the complex and that will
mediate transcription.
- After Phosphorylation of CTD, transcription is initiated and then the Pol starts and
elongates. The mediator and everything else don’t go.
- Processing factors and capping and splicing and more go with the mRNA and process it
during transcription. IT HAPPENS WHILE TRANSCRIPTION IS GOING ON.
- Elongation and processing factors tag along on the CTD tail and process along the way
(ex. splicing).
- Transcription of the ribosomal RNA gene
- UBF (Initiation/Transcriptional Factor) , SL1 (Transcription Factor), and Pol I are
on the promoter (made in the nucleolus).
- RNA Pol I (18S, 5.8S, 28S)
- RNA Pol III (for 5S rRNA and tRNA) (5S is made out of the nucleolus and then
joined later)
- RNA pol binds to promoter → General TFs get involved → CTD forms and RNA
pol II synthesises 5’ → 3’.
- U6 snRNA are a part of the spliceosome (mainly RNA but has proteins). RNA
splices out introns.
- There’s another RNA Polymerase inside of mitochondria.
Document Summary
Identified using in vitro systems id"d 5 general tfs (tfiix) (all required for. Tfiid: tbp (tata-binding protein) - binds tata box (in pro and euk) Tfiib and tfiif recruit rna pol ii to the site. Tfiih two roles: 1) helicase 2) ctd kinase help the preinitiation complex to start the transcription. Tfiid is made up of tata-binding protein (tbp) - binds tata box and. Tafs (tbp-associated factors) - bind other elements (lnr, dce, etc. ) Tfiib and tfiif recruitment of rna pol ii. Tfiih two roles: 1) helicase 2) ctd kinase. It has 52 repeats in human (the serine in the 5th position phosphorylates and that starts the transcription) so no phosphorylation, no transcription (phosphorylation of ctd is the go) Additional factors contribute to transcription initiation within cells. Mediator facilitates interactions between rna pol ii and regulator factors. Complex that holds everything together until it starts.
