lec 14-15 - Key concepts Each stage of translation requires...

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Key concepts Each stage of translation requires specific proteins called initiation factors , elongation factors , and release factors . Initiation involves recruitment of the initiator tRNA to the small ribosomal subunit, recruitment of the mRNA, recognition of the start codon, and recruitment of the large ribosomal subunit. Recruitment of the mRNA usually involves an interaction of an initiation factor (eIF4E) with the 5’ cap structure of mRNA. Cap-independent translation can also occur.
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Key concepts Elongation proceeds through a repetitive 4-step cycle: binding of incoming aminoacyl-tRNA to the A site, conformation shift of ribosome accompanied by release of previously used tRNA from the E site, transfer of the growing peptide chain to the incoming amino acid, and translocation of the ribosome to the next codon. Termination factors (release factors) recognize stop codons and cleave the polypeptide from tRNA. Efficiency of protein synthesis is increased by simultaneous translation of a single mRNA by multiple ribosomes (polyribosomes, or polysomes). Re-initiation of protein synthesis is promoted by an interaction between eIF4G and PABP, which brings the 3’ and 5’ ends of the mRNA close together (circularizing the mRNA).
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Post-Transcriptional Gene Silencing
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RNA interference First discovered as an artificially-induced experimental phenomenon Injection of antisense RNA targeted against a specific mRNA into a cell or embryo represses translation of the target mRNA. Surprisingly, injection of perfectly-matched double-
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This note was uploaded on 12/07/2010 for the course BIO BIOL 200 taught by Professor Frogatto during the Fall '10 term at McGill.

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lec 14-15 - Key concepts Each stage of translation requires...

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