BIOS E-1a Lecture 13 110911 annotated

BIOS E-1a Lecture 13 110911 annotated - Lecture 13...

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Lecture 13: Eukaryotic Gene Regulation, continued… Reading: Chapter 11 1
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2 1. One or more activator proteins may stimulate the ability of RNA polymerase to initiate transcription. 2. One or more repressor proteins may inhibit the ability of RNA polymerase to initiate transcription. 3. The function of activators and repressors may be modulated in several ways. These include the binding of small effector molecules, protein–protein interactions, and covalent modifications. 4. Activator proteins are necessary to promote the loosening up of the region in the chromosome where a gene is located, thereby making it easier for the gene to be recognized and transcribed by RNA polymerase. 5. DNA methylation usually inhibits transcription, either by preventing the binding of an activator protein or by recruiting proteins that cause the DNA to become more compact. Combinatorial control
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3 Eukaryotic structural genes • 3 features found in most promoters – TATA box • 5’ – TATAAAA – 3’ • 25 base pairs upstream from transcriptional start site • Determines precise starting point for transcription – Transcriptional start site • Where transcription begins • With TATA box forms core promoter – By itself results in low level basal transcription – Regulatory or response elements • Recognized by regulatory proteins that control initiation of transcription • Enhancers and silencers
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4 Common sequences in promoter elements
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5 3 proteins needed for transcription 1. RNA polymerase II 2. 5 different general transcription factors (GTFs) 3. Large protein complex called mediator
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6 • GTFs and RNA polymerase II must come together at core promoter before transcription can be initiated • Preinitiation complex: assembled GTFs and RNA polymerase II at the TATA box – Form basal transcription apparatus • Mediator composed of several proteins – Partially wraps around GTFs and RNA polymerase II – Mediates interactions with activators or repressor that bind to enhancers or silencers – Controls rate at which RNA polymerase can begin transcription
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7 • Activators bind to enhancers • Repressors bind to silencers • Regulate rate of transcription of a nearby gene • Most do not bind directly to RNA polymerase II
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8 • 3 ways to control RNA polymerase II 1.Activators and repressors commonly regulate function of RNA polymerase II by binding to GTFs (including TFIID) or mediator
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9 2. Control RNA polymerase II via mediator – Activators stimulate the function of
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This note was uploaded on 02/09/2012 for the course BIOLOGY 102 taught by Professor Anderson during the Spring '11 term at Harvard.

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BIOS E-1a Lecture 13 110911 annotated - Lecture 13...

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