Control of gene expression 1 Flashcards
Initiation of transcription - general principles:
RNA polymerase interacts with other proteins (transcription factors) when it binds to the promoter
The most basic promoter is required for RNA polymerase to bind and initiate transcription at the appropriate site
Additional control sequences can determine WHEN a gene is transcribed
What are cis-acting regulatory regions?
Cis-acting regulatory regions are DNA sequences recognised by proteins. All regulatory regions of class II genes contain two kinds of essential DNA sequences
What are enhancers?
are regulatory sites that can be distant from the promoter
what are promoters?
very close to the protein-coding region and includes the initiation site, where transcription begins and a “TATA” box
What are trans-acting proteins?
Trans-acting proteins (transcription factors) bind to the promoter and enhancer to control transcription from the gene:
What are basal factors?
RNA pol II bind to the promoter
Eukaryotic RNA polymerase II can only bind promoters with the the help of transcription factors…
TATA-box binding protein (TBP) binds to the TATA box
2. TBP recruits TFIID complex and TFIIB to the promoter
RNA pol II and further transcription factors bind to the promoter to give the basal transcription complex
What are activator proteins?
Activator proteins bound to enhancers interact with the basal transcription complex
What is Gal4 system of yeast?
a paradigm for eukaryotic gene regulation
Describe control of transcriptional invitation in eukaryotes
Transcription factors bind promoter sequences and form the basal transcription complex with RNA polymerase II.
Activator proteins bind upstream enhancer sequences and interact with the basal transcription complex.
Gal4 activates multiple galactose-inducible genes in yeast.
Describe chromatin structure?
Short region of DNA double helix, beads on a string form of chromatin
provides a brake on runaway basal transcription
How can core histones be modified?
Covalently on their N-terminal tails
