module 7 lec 12 Flashcards
What are activators in transcription regulation?
Activators are transcription factors that help recruit basal factors and RNA polymerase II to the promoter to initiate transcription.
How do activators assist in transcription initiation?
Activators recruit basal factors and RNA polymerase II to the promoter, facilitating the start of transcription.
What is the role of coactivators in transcription regulation?
Coactivators are proteins that help activate transcription by altering chromatin structure or recruiting transcription machinery.
How do coactivators affect chromatin?
Coactivators, such as histone acetyl transferases (HATs), modify chromatin structure to make it more accessible for transcription.
What is the role of Histone Acetyl Transferases (HATs) in transcription
HATs add acetyl groups to histones, which relaxes chromatin and promotes transcription.
How do chromatin remodeling complexes assist transcription?
Chromatin remodeling complexes reposition or restructure nucleosomes, making the DNA more accessible for transcription.
What are the typical domains of an activator protein?
An activator protein usually has 2 or 3 domains:
DNA binding domain
Activation domain (for basal factors or coactivators)
Sometimes a dimerization domain
What is the function of the DNA binding domain in activators?
The DNA binding domain allows the activator to bind to specific DNA sequences in the promoter or enhancer regions to regulate transcription.
What is the role of the activation domain in activators?
The activation domain interacts with basal transcription factors and coactivators to initiate transcription
What is a leucine zipper in transcription factors?
A leucine zipper is a common structural motif in activators, involved in protein dimerization, where leucines form hydrophobic interactions.
What are helix-turn-helix domains?
Helix-turn-helix is a well-conserved DNA binding motif found in activators like the Lac repressor, allowing them to interact with DNA.
What is the function of a zinc finger in transcription factors?
A zinc finger is a DNA-binding domain that uses zinc ions to stabilize the structure, allowing the activator to bind to specific DNA sequences.
What is a leucine zipper in transcription factors?
A leucine zipper is a structural motif in transcription factors that facilitates dimerization, where two protein subunits bind together through hydrophobic interactions between leucine residues.
How does the leucine zipper work?
It helps two protein subunits bind together, enabling DNA binding and gene activation.
What amino acid is key in leucine zippers?
Leucine residues spaced every 7th amino acid.
Why is leucine zipper important for transcription?
It stabilizes DNA-protein interactions and enhances transcription factor binding.
What do repressors do in transcription?
Repressors prevent gene activation by blocking RNA pol II binding or recruiting corepressors.
How do repressors block transcription?
They recruit corepressors that modify histones, keeping chromatin in a closed state.
What is the structure of a repressor?
Similar to activators, with DNA binding and repression domains.
How do repressors inhibit activators?
They interfere with activators’ ability to recruit RNA pol II or other transcription factors.
What is indirect repression?
Repressors prevent transcription by interfering with activator functions, not directly blocking RNA polymerase.
What is the role of transcription factors in gene regulation?
Transcription factors help regulate gene expression by binding to specific DNA sequences, often at enhancers or promoters.
How many human genes are estimated to encode transcription factors?
About 2,000 out of 25,000 human genes encode transcription factors.
Where does cell-specific transcriptional regulation often occur?
At the enhancer regions of DNA
Can a single gene have multiple enhancer
Yes, a gene may contain several enhancers, each active in different cell types or under specific conditions.
What are enhancers in gene regulation?
Enhancers are DNA regions that increase the transcription of a gene, often influencing tissue-specific gene expression.
What is the role of allosteric interactions in transcriptional regulation?
Allosteric interactions involve changes in the shape or activity of transcription factors, often in response to binding of small molecules or other proteins.
How do transcription factor modifications regulate gene expression?
Modifications, such as phosphorylation, alter the activity, stability, or DNA-binding ability of transcription factors, influencing gene expression.
What is an example of a transcription factor modification?
Phosphorylation by kinases is a common modification that can activate or deactivate transcription factors.
What are transcription factor cascades?
Transcription factor cascades are a series of sequential activations, where one transcription factor activates others, amplifying the gene expression response.
