Talk about the N-glycosylation role of RER.

Sugar linked to N of ِside-chain Asparagine (oligosaccharide) necessary for maturation and activity (glucose, N-acetylglucosamine, mannose...) transferred to specific asparagine and synthesized by specific enzymes (oligosaccharyl transferrases, glycosyl transferrases) molecule that carries oligosaccharide before transfer is lipid called (dolichol) that accepts oligosaccharide prior to its transfer to asparagine. (all enzymes are in membrane of RER)