E8-splicing_processing

E8-splicing_processing - Simple summary of the capping and...

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Unformatted text preview: Simple summary of the capping and splicing process Overview of capping and splicing of Pol II transcripts (Splicing reactions can occur co- or post- transcriptionally.) TFIIH phosphorylates CTD CPSF is transfered from TFIID to the CTD of Pol II GT and MT bind to CTD and cap message. Elongation factors bind CTD. CTD may serve as an activator of these enzymes. CTD is a platform for splicosome recruiting factors. CPSF and CstF bind CTD When protein-encoding genes are transcribed by Pol I or Pol III, the transcripts are not efficiently spliced. Co-transcriptional splicing site of transcription initiation intron loops released transcript 200 nm Miller chromatin spreading The CTD of Pol II serves as a platform for assembly of elongation and maturation factors Splicing can be inhibited by anti-CTD antibodies, or by free CTD polypeptide. Pol II is immunoprecipitated by anti-SR and anti-SM antibodies. CPSF and CstF are retained on CTD affinity columns. Capping of 5 end occurs during transcript elongation Slightly different Caps are put onto different messages Cleavage specificity factors, cleavage stimulatory factors, and polyA polymerase form a protein complex the interacts with the polymerase CTD and the nascent transcript. The identity of the nuclease remains elusive. There are 4 basic types of splicing 1. Group I introns (rRNA, organelle, phage) 2. Group 2 introns (bacteria, organelle) 3. Group 3 introns (mRNA) 4. Group 4 introns (tRNA) Summary of Group I Intron Splicing Relatively rare in nature Examples in eukaryotes, prokaryoyes and archaea. many are self-splicing in vitro some require proteins in vitro some encode proteins that aid in splicing and retrotransposition some are mobile size and number of ORFs is variable. The spliced Tetrahymena rRNA intron is a nucleotidyl transferase enzyme oligonucleotide disproportionation reaction (shown at left) also: sequence specific endoribonuclease nucleotidyl transferase with dinucleotides RNA ligase with external template phosphatase Significance of RNA having catalytic activity...
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This note was uploaded on 02/17/2012 for the course CHEM 212 taught by Professor Staff during the Fall '10 term at Rutgers.

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E8-splicing_processing - Simple summary of the capping and...

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