Lecture 10 - Transcriptional Regulation 2 Flashcards
(41 cards)
Promoter
Sequence of DNA near the 5’ end of the coding region of a gene where RNA polymerase binds and initiates transcription
Two important sequences in a promoter
- Recognition sequence
2. TATA box
Recognition sequence
The sequence recognized by RNA polymerase
TATA box
Called this because it is rich in AT base pairs. Sequence closer to the transcription initiation site where DNA begins to denature so that the template strand can be exposed
Transcription cannot start until what happens
Until transcription factors have assembled on the chromosome
Explain what happens before RNA polymerase II can bind
- Transcription factor TFIID binds to the promoter at the TATA box changing its own shape and that of the DNA
- Other transcription factors join it to form a transcription complex
- RNA polymerase II binds only after several transcription factors are already bound to DNA
Enhancers
Positive regulators which bind activator proteins
Silencers
Negative regulators which bind repressor proteins
What determines the rate of transcription?
Efficiency of binding of GTFs to the core promoter DNA sequences determines levels of transcription (promoter strength)
Remodelling of chromatin
Increases the accessibility for trancription
Transcriptional regulation
Controlling when and how often a given gene is trancribed
RNA Processing control
Controlling the splicing and processing of RNA transcripts
RNA transport and localisation control
Selecting which completed mRNAs are exported from the nucleus to the cytosol and determining where in the cytosol they are localized
Translational control
Selecting which mRNAs in the cytoplasms are translated by ribosomes
Post-translational modification
Control of protein like phosphorylation, acetylation, ubiquitination of them
Protein activity control
Selectively activating, inactivating, degrading, or localizing specific protein molecules after that have been made
Core promoter binding sites for TFIIB
TFIIB can bind the BRE elements
Core promoter binding sites for TFIID
TBP subunit of TFIID can bind the TATA box
mRNA degradation control
Selectively destabilizing certain mRNA molecules in the cytoplasm
Transcription regulators
Recognize specific sequences of DNA that are often called cis-regulatory sequences. This binding ultimately specifies which genes are to be transcribed and at what rate
cis-regulatory sequences
They must be on the same chromosome (in cis) to the genes they control
What do transcriptional activators or repressors do?
They bind to DNA regulatory elements (promoter proximal or distal sequences) and either enhance or repress transcription levels directed by the basal transcription factors and RNA polymerase at the core promoter
What type of transcription factors are activators and repressor proteins?
Sequence-specific transcription factors
What can DNA bending do?
It can bring the activator protein, that was bound to an enhancer element far from the promoter, into contact with the transcription complex
