Folding and assembly of proteins synthesized in the endoplasmic reticulum is closely monitored by a quality control apparatus that diverts folding-defective products to the cytosol to be degraded by the ubiquitin-proteasome system by a process known as endoplasmic reticulum-associated degradation (ERAD). The long-term goal of this project is to elucidate the mechanisms by which ERAD recognizes and destroys its targets. In the previous funding period we successfully implemented a large scale proteomic analysis of the mammalian ERAD system that allowed us to create the first comprehensive course-grained map of the mammalian ERAD interactome in mammals. We used these data to identify new ERAD components and protein complexes and to propose a novel hypothesis in which mannose trimming of core N-glycans orchestrates the ordered recognition and delivery of folding defective proteins. The studies proposed in the present application seek to test this hypothesis, to refine the ERAD interaction network and discover new ERAD components not based on orthology to fungi. To this end we will exploit emerging technologies such as gene editing, ultrahigh density shRNA and genetic interaction mapping.
The proposed studies will investigate the process by which misfolded or damaged proteins in the secretory pathway are identified and destroyed. Since mutations which influence protein folding underlie most genetic diseases, understanding the cellular mechanisms that defend against such mutations is critical to our understanding of the molecular basis of genetic disease.
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