Hoatlin: Fundamentals: Difference between revisions
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*Are transcription factors, basal transcription factors, basal factors all the same thing? | *Are transcription factors, basal transcription factors, basal factors all the same thing? | ||
;Answer | ;Answer | ||
*Yes. (see pg 239 in your reading, Essential Cell Biology pg 239) and the lecture notes that describe initiation of transcription with the stepwise assembly of proteins at the promoter (the TFIIA, TFIIB etc plus RNA polymerase) and slide 24 of the last lecture where the first point is “Basal transcription factors: TATA-binding protein TFIIB, TFIIA, TFIIE, TFIIH etc.” | * Yes. (see pg 239 in your reading, Essential Cell Biology pg 239) and the lecture notes that describe initiation of transcription with the stepwise assembly of proteins at the promoter (the TFIIA, TFIIB etc plus RNA polymerase) and slide 24 of the last lecture where the first point is “Basal transcription factors: TATA-binding protein TFIIB, TFIIA, TFIIE, TFIIH etc.” The basal transcription factors are a subset of all transcription factors. | ||
;Question | ;Question | ||
*It is not clear what the functional classes of transcription factors are. | *It is not clear what the functional classes of transcription factors are. | ||
;Answer | ;Answer | ||
Transcription factors can be constitutively-active – present in all cells at all times or can be conditionally-active – requires activation (e.g., cell specific or signal-dependent). | |||
;Question | * Slide 25 has the overview of the list of proteins that regulate transcription (as follows): | ||
**Basal transcription factors | |||
***TATA-binding protein TFIIB, TFIIA, TFIIE, TFIIH etc. | |||
**DNA-Binding Factors | |||
***Signal-regulated proteins: posttranslational modifications (phosphorylation). | |||
***Nuclear Hormone Receptors: require ligand binding. | |||
**Co-regulatory protein complexes | |||
***Interact with DNA binding proteins, but not (necessarily) with DNA | |||
***TBP-Associated Factors (TAFs) | |||
***Histone modifying enzymes. | |||
***Chromatin remodeling factors | |||
;Question | |||
*I was a bit confused with: Using a steroid receptor as an example, explain how gene expression can be regulated by hormonal signals. | |||
;Answer | |||
*Just a general description from the standpoint of transcription can be found in the related text and in the figure in the lecture notes: "Reciprocal regulation of transcription. In the absence of ligand, nuclear hormone receptors repress transcription through the action of co-repressor complexes with associated HDAC activity. Ligand-induced conformational changes lead to dissociation of co-repressor complexes with recruitment of co-activator/HAT complexes. (from Glass and Rosenfeld, Genes Dev. 14:121-41, 2000)" | |||
;Question | |||
*Cis elements- these are regulatory sequences on DNA. Can they be both enhancers and silencers? Does their proximity to the gene matter to still be considered "cis"? | *Cis elements- these are regulatory sequences on DNA. Can they be both enhancers and silencers? Does their proximity to the gene matter to still be considered "cis"? | ||
;Answer | |||
*Yes, they can be both enhancers and silencers, and can be very far away but on the same piece of DNA. | *Yes, they can be both enhancers and silencers, and can be very far away from the promoter, but on the same piece of DNA. | ||
;Question | ;Question | ||
*Regarding constitutive and inducible enhancer elements, it was my understanding that enhancer refers to the DNA sequence, whereas activator refers to the DNA binding protein, so I’m not sure of what a constitutive and inducible enhancer is. | *Regarding constitutive and inducible enhancer elements, it was my understanding that enhancer refers to the DNA sequence, whereas activator refers to the DNA binding protein, so I’m not sure of what a constitutive and inducible enhancer is. |
Revision as of 21:19, 23 January 2012
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Questions and Answers
Transcription factors can be constitutively-active – present in all cells at all times or can be conditionally-active – requires activation (e.g., cell specific or signal-dependent).
That's how PARP1 inhibitors are relatively selective in killing the HR deficient tumor cell but not the wild-type cell (which is competent for HR)
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