Biology 3597A/B Lecture Notes - Lecture 17: Nuclear Pore, Nonsense Mutation, Rna Editing
25 Jan 2020
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Mrna must be exported from the nucleus. Once exported, translation will occur (important step) mrna turnover and quality control. Checkpoint #2: quality check in the cytoplasm: before translation premature stop codon triggers nonsense-mediated decay. Checkpoint #3: after translation: eventually all mrna is degraded mrnas with nonsense mutations are degraded very quickly mrna turnover and quality control in the nucleus. Exosomes degrade mrnas that don"t pass quality control (purple box) If mrnp is defective, it is recognized by a protein complex called tramp : this leads to the recruitment of the exosome (circle of pac-men , the pac-men then chew up the defective rna. Quality check #1: trex/mrnp formation: trex interacts with tap/nrx1. If this works, rna will be exported out of the nucleus. If not, rna is targeted by tramp and brought to the exosome to be degraded. Looks good enough to pass through the membrane into the cytoplasm for translation.
