Spring 09 lecture 28

Spring 09 lecture 28 - Another focus group: Thursday July...

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11 Another focus group: Thursday July 17th at 10-11:30 in MC 4051 (coffee and donuts provided) Same contact info: Kelvin Siu <[email protected]>
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22 Control of gene expression through RNA processing and post- Learning Objectives Alternative splicing and trans-splicing Describe role of transport through nuclear pore in contro of gene expression Describe different mechanisms of post- transcriptional/pre-translational control of gene expression
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33 Transcription initiation Direct influence of A and R on initiation Activators (A), repressors (R) and remodeling proteins and chromatin structure Methylation Hormones and other “external” signals RNA processing Capping and polyadenylation Alternative splicing and trans-splicing Transport through the nuclear pore Posttranscriptional / pretranslational control (events on/with mRNA before ribosomes) Localization of mRNA RNA editing Post-transcriptional silencing by siRNA or miRNA Translational control switch RNA stability (degradation and stabilization) Translational control (mRNA/ribosomes) Phosphorylation of translation initiation factors Upstream AUG codons IRES Protein activity control Posttranslational modification and transport Control of gene expression: overall
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44 Summary of processing of Eukaryotic mRNAs: spots for control of gene 5’ capping : 5’ cap (7-methylguanosine) added by enzyme that associates with CTD tail of RNAP II Polyadenylation occurs when the polyadenylation signal sequence is recognized (AAUAAA); necessary enzymes involved in polyadenylation are brought to polyA signal sequence by CDT tail In eukaryotes : removal of non-coding regions - splicing - occurs via a complex called the spliceosome that catalyzes two transesterification reactions and splices the introns out leaving the exons ligated together (also, role of CTD tail ). Processing control
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55 Transcription Units in Eukaryotes Eukaryotes can have simple and complex transcription units Processing control Complex transcription unit Simple transcription units D constitutive splicing Complex transcription units alternative splicing At least 5% of eukaryotic transcription units are complex
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66 Regulation of mRNA processing Expression of complex transcription units is controlled through regulation of splicing and cleavage/polyadenylation (through using alternative polyadenylation elements) & alternative processing Alternative processing of complex pre-mRNAs is mostly regulated according to cell type , developmental stage or change in environmental conditions . For example, one mRNA is expressed only in one cell type while the alternative is only expressed in another cell type etc. Complex transcription units ±
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This note was uploaded on 08/03/2009 for the course BIOL BIOL308 taught by Professor Miskovic during the Spring '09 term at Waterloo.

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Spring 09 lecture 28 - Another focus group: Thursday July...

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