BIO230H1 Lecture Notes - Lecture 6: Nuclear Pore, Aconitase, Critical Role

• School: UTSG
• Department: Biology
• Course: BIO230H1
• Professor: Kenneth Yip

Document Summary

Mrna quality control in the cytosol: some mrnas are incompletely processed or damaged in the cytosol, need to prevent production of aberrant protein which can be toxic to cell. Review of translation: trnas match amino acids to codons (3 nucleotides) in the mrna. Mrna quality control in the cytosol eukaryotes: translation initiation machinery recognizes the 5" cap and poly-a tail, eukaryotic initiation factors (eifs) Recruit small ribosomal subunit which will initiate translation at first aug downstream of 5" cap (some exceptions) Ensures that both ends of mrna are in tact: exon junction complex also stimulates translation since it ensures proper splicing, nonsense-mediated mrna decay. Surveys for nonsense (stop) codons in the wrong place . Stop codon is in the last exon. No ejc bound when ribosome reaches stop codon. Ribosome binds mrna as it emerges from nuclear pore. Ejcs remain on mrna when ribosome reaches stop.