Lecture 20 Flashcards
Explain dimerization domains (2 parts)
The basic region contacts the DNA.
The Leu-zipper acts as the dimerization on the hydrophobic interface.
Homodimers
2 proteins are the same
Heterodimers
2 proteins are different
Steroid receptor
Activation domain. Once the ligaand binds, tx factors are activated, and the structure change occurs.
bHLH
basic protein HELIX-LOOP-HELIX
What happens when 2 bHLHs bind?
dimerization occurs and the basic region binds to DNA
What happens when a nonbasic HLH and bHLH bind?
the heterodimer can’t bind to the DNA
What is required for RNA pol II to initiate transcription?
TFII X
what sequence is at the initiator of POL II
Py(2) CA Py(5)
Py’s are
pyrimidines
Inr
Initiator
DPE
downstream promoter element
in promoters w/o TATAA box
2 types of core promoters
- TATA
2. TATA less
What does the core promoter for RNA pol II have
INR region
either a tATa or DPe
TFIID
TBP (tata bind proteins)
TAFS (TBP associated factors)
TBP
tata binding protein
TAFS
TBP associated factors
Where does TBP bind?
To the TATA box in the minor groove
What happens when TBP binds?
The DNA bends giving more exposure
Step 1 of pol II
TBP binds to TAFS to form TFIID
Step 2 of pol II
TF2 F and TFII B bind
Step 3 of pol II
TFII E comes in
Step 4 of pol II
TF II H comes in with kinase activity and puts - charges on carboxy terminal domain
Step 5 of pol II
Repulsion event causes transcription to begin and RNA pol II takes off
What are required to melt DNA to allow the polymerase to move?
TF II E and H
Explain the cycle of phosphorylation
- Recruitment of RNA pol II
- Phosphorylation recruits enzymes to cap 5’ end
- Elongation occurs
- Dephosphorylate and cycle continues
What does the C terminal domian have that can be phoshorylated/
Threonine
Tyrosine
Serine
Carboxy Terminal Domain
coordinates processing and export of tRNA from nucleus
Which promoters do enhancers activate?
the ones nearest itself
UAS
upstream activating sequence found in yeast
behaves like an enhancer but only works upstream
What happens if the two molecules are catenated?
Transcription can occur! Enhancers can be made to work in trans as long as it’s constrained to be in proximity of the promoter.
