... ER until they are correctly folded and assembled by chaperones, an event that is signalled by the permanent removal of the terminal glucose residue by glucosidase II. Misfolded or unassembled subunits are reglucosylated by a glucosyltransferase. This allows them to rebind Clx and enter a cyclical pathway until they achieve their correctly folded structure and are released. Glycosylation and ER associated degradation: If a protein remains in a misfolded state, it is eventually targeted for retrograde transport and can be eliminated directly in a process known as ER associated degradation (ERAD). Once again, it is the glycosylation state of the misfolded protein that will target it for degradation. Indeed, ERAD is initiated by the action of manosidase I. This enzyme removes a single mannose residue from the oligosaccharide precursor so that it carries the glycan motif GlcNAc2Man8. The latter then gets reglucosylated and readily binds Clx. With such a glycan structure, the misfolded ...

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