Set 17: Eukaryotes Enzymes, parts of promoters, Basal factors, TBPs, Enhancers & Repressors, how they work, Gene Silencing.
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Set 17: Eukaryotes
Eukaryotes generally don’t organize genes into operons.
RNA Polymerases recognize specific promoters
RNA Polymerase II does the transcribing.
Core promoter: absolutely required for initiation of
Promoter Region consists of:
TAATA box is -30 position and not same sequence
(remember -10 position in prokaryotes)
CAT Box -100 position
GC Box -200 position
(See slide 8)
Enhancer: regulatory site
Basal Factors: required for binding to the promoter to
maintain a basal level of transcription. They bind to the
One Basal factor is called TBP = TATAT binding protein
TBP comes in, binds to promoter, TAFs (TATAT binding
protein association factors) bind
Core promoter: absolutely required for initiation of transcription. Taata box is -30 position and not same sequence (remember -10 position in prokaryotes) Basal factors: required for binding to the promoter to maintain a basal level of transcription. One basal factor is called tbp = tatat binding protein. Tbp comes in, binds to promoter, tafs (tatat binding protein association factors) bind. Activator proteins: bind to enhancer sequences to increase transcription. Two binding domains: dna binding domain, transcription-activation domain (see slide 13) The activator, which is bound to the promoter, also binds to the tbp (dna curves around) and transcription increases. **most eukaryotic activators have to for dimers to function. Transcription factor must bind to testosterone before it can bind to enhancer because testosterone causes the transcription factor to change into its necessary shape. This allows enhancer to bind to basal factors. **enhanced leved of transcrpition** repressors - diminish transcriptional activity. Could bind to enhancer which blocks activator (competitive)