BIOL 200 Lecture 27: Protein Folding and Quality Control
Document Summary
First round of translation is essential for quality control; diff. from all the other rounds, since it"s going to encounter the mrna for the first time i. e. the pioneering round of translation. As the mrna leaves nuclear pore, all/most nuclear proteins should be removed from the mrna. This is by activity of a helicase that sits at the nuclear pore. When mrna reaches cytoplasm, some srs could still be attached to the mrna. Sr proteins worked in transcription regulation, to define the exons such that introns could be spliced out properly. Remaining sr proteins need to be removed during first round of translation, or nmd will occur! In this 1st round, all remaining export factors (proteins) must be removed by the ribosome, as it works its way through the mrna. Dangerous for the cell; might make a protein that"s half-functional; a truncated protein.
