TRANSCRIPTION
Initiation: To begin transcribing a gene, RNA polymerase binds to the DNA of the gene at a region called
the promoter. Basically, the promoter tells the polymerase where to "sit down" on the DNA and begin
transcribing. A promoter contains DNA sequences that let RNA polymerase or its helper proteins attach
to the DNA.
Enzymes involved:
- RNA Polymerase I -> responsible for copying a DNA sequence into an RNA sequence
- RNA polymerase II -> unspooling the genetic program in the form of protein-coding mRNAs
and some small non-coding RNAs. RNA polymerase II requires a set of general transcription
factors.
- TF2D – TBP subunit recognizes TATA box
- TF2B – recognizes BRE sequence
- TF2D and TF2B bring RNA Pol II and TFIIH (and other TFIIs) to the promoter
- TF2H – unwinds DNA, initiates elongation step by promoting release of some TFIIs
In general TF2D and TF2B bring RNA pol to the DNA and they also bring TF2H to the
DNA.
The CTD is an amazing sequence arrangement at the end of the RNA pol II. The CTD
consists of up to 52 repeats. This portion of RNA pol II is involved in initiation of DNA
transcription, capping of RNA transcript, and attachment to splice some.
CTD (The C-terminal repeat domain): an unusual extension appended to the C terminus of the
largest subunit of RNA polymerase II; it serves as a flexible binding scaffold for numerous nuclear factors
(these are factors that control DNA transcription).
TF2H has 2 roles:
i.) Helicase activity: activity important for elongation, as it allows the unwinding of
DNA.
ii.) Kinase: phosphorylates the tail of RNA polymerase 2 at serine 5 and serine 2. This
phosphorylation is important for release of phosphates, so that RNA polymerase can
move across the strand and transcribe the strand.
Initiation: To begin transcribing a gene, RNA polymerase binds to the DNA of the gene at a region called
the promoter. Basically, the promoter tells the polymerase where to "sit down" on the DNA and begin
transcribing. A promoter contains DNA sequences that let RNA polymerase or its helper proteins attach
to the DNA.
Enzymes involved:
- RNA Polymerase I -> responsible for copying a DNA sequence into an RNA sequence
- RNA polymerase II -> unspooling the genetic program in the form of protein-coding mRNAs
and some small non-coding RNAs. RNA polymerase II requires a set of general transcription
factors.
- TF2D – TBP subunit recognizes TATA box
- TF2B – recognizes BRE sequence
- TF2D and TF2B bring RNA Pol II and TFIIH (and other TFIIs) to the promoter
- TF2H – unwinds DNA, initiates elongation step by promoting release of some TFIIs
In general TF2D and TF2B bring RNA pol to the DNA and they also bring TF2H to the
DNA.
The CTD is an amazing sequence arrangement at the end of the RNA pol II. The CTD
consists of up to 52 repeats. This portion of RNA pol II is involved in initiation of DNA
transcription, capping of RNA transcript, and attachment to splice some.
CTD (The C-terminal repeat domain): an unusual extension appended to the C terminus of the
largest subunit of RNA polymerase II; it serves as a flexible binding scaffold for numerous nuclear factors
(these are factors that control DNA transcription).
TF2H has 2 roles:
i.) Helicase activity: activity important for elongation, as it allows the unwinding of
DNA.
ii.) Kinase: phosphorylates the tail of RNA polymerase 2 at serine 5 and serine 2. This
phosphorylation is important for release of phosphates, so that RNA polymerase can
move across the strand and transcribe the strand.
