Eu TFs Flashcards
What are transcription factors?
Any protein (other than RNA polymerase) required to initiate or regulate transcription
What are GTFs and STFs?
GTF = General (basal) TFs
- participate in the formation of the basal transcription complex near the start site (e.g. TFII etc.)
= start transcription with the help of RNA polymerase accurately
STF = Specific TFs
- stimulate (or repress) transcription of particular genes by binding to their regulatory sequences
= help with getting the right amount of product made at the right place and time
How do TFs bind to DNA?
By specific AA side chains: base-interactions
E.g. specific AA sequences on DNA alpha helix are able to interact with a series of base pairs
- A typical DNA-protein interface would have 10-20 contacts
How do AAs interact with base pairs of DNA + example?
Hydrogen bonding.
E.g. asparagine and arginine side chains can get involved with hydrogen bonding
Need series of AAs in right combination within protein that recognise base pairs to give right 3D arrangement (of those AAs) = specific binding to specific DNA sequence
How is specificity achieved through protein interactions with DNA?
When a particular protein interacts with a particular DNA sequence then just one AA interaction with one base pair is enough to give specificity needed.
Which DNA sequences regulate gene transcription?
1) Promoters
– close to transcription start site (usually a few hundred base pairs of start site)
which include specific sequences.
Other reg sequences are much further away.
2) Enhancers/silencers
– distant from transcription start site
3) Insulators
– prevent interference between transcription units
- stop enhancers from interfering with other genes
What and where is the promoter?
- DNA sequence that initiates and regulates transcription
- Mainly upstream (5’) of the transcribed sequence
How can STFs act with the TC?
Can act by interacting directly or indirectly with the transcription complex
What is the regulatory promoter?
Serves to increase transcription (or decides which cells are going to be transcribed in)
How do STFs act with the TC?
Can act by interacting directly or indirectly with the transcription complex.
What are ‘housekeeping’ genes?
- Genes expressed in all cells e.g. histone genes
What are ‘housekeeping’ genes?
- Genes expressed in all cells e.g. histone genes
What do the CAAT box, GC box and octamer all have in common?
They have a distinct pattern of nucleotides (consensus) found in the promoter region of some eukaryotic genes
What do the CAAT box, GC box and octamer all have in common?
They have a distinct pattern of nucleotides (consensus) found in the promoter region of some eukaryotic genes
What is the core promoter?
Sequences you need to get any appreciable transcription (e.g. took that piece of DNA and isolated it and put it in a test tube - core promoter is what you would need to get transcription)
