Chromatin Modification 2

Chromatin Modification 2 - Chromatin Modification I. R NAP,...

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Chromatin Modification I. RNAP, TFII, and mediators are unable to assemble on packaged chromatin a. When chromatin is condensed, essentially the gene is “off” b. Histone tails are more accessible when extended than when they are condensed c. Activators help accelerate the rate of transcription initiation, and also attract general TFs, mediator, and RNAP II at the promoter i. The mediator provides an extended contact area for gene regulatory proteins d. Gene regulatory proteins (TF factors) initiate chromatin opening II. Eukaryotic gene activator proteins modify local chromatin structure a. In general, transcription can be repressed when a promoter and flanking sequences are wound up in a nucleosome and are inaccessible to RNA polymerase b. gene activator proteins can bind directly to DNA that is packaged in unmodified chromatin and subsequently promotes transcription initiation by changing the chromatin structure of regulatory sequences & promoters c. local chromatin structure is altered with the help of: i. histone modification enzymes ii. ATP-dependent chromatin remodeling complexes (nucleosomal sliding, removal, replacement) iii. Histone chaperones
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d.
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This note was uploaded on 04/12/2010 for the course MCDB 165B taught by Professor Nakano during the Winter '10 term at UCLA.

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Chromatin Modification 2 - Chromatin Modification I. R NAP,...

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