BIOL 2021 Chapter 12.2: protein modification in ER
28 Jan 2018
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Document Summary
Modifications to proteins takes place in the er lumen. The modifications that occur in the lumen will face the cytosol when transported out since they are topologically equivalent. Protein disulfide isomerase (pdi): enzyme that converts sh to s-s in the er lumen so that proteins can fold properly. More modifications to the sugars occur in the golgi. A: caused by misfolded proteins that form aggregates and disrupt cellular functions (especially in the nervous system) Misfolded proteins can form aggregates which is dangerous for cells. Misfolded proteins are exported out of the er and are destroyed by a proteosome in the cytosol. Mannose trimming acts as a timer and detects amount of mannose on the core oligosaccharide. If the protein has been going through the cycle too many times, too much mannose gets trimmed off. The unfolded protein will then be exported to the cytosol through an alternative pathway (not through vesicles)
