Which of the following events occurs in the rough endoplasmic reticulum?

The rough endoplasmic reticulum (RER) is the site of core glycosylation of proteins using the membrane-bound lipid carrier, dolichol, catalyzed by an oligosaccharide transferase. This is N-linked glycosylation, which occurs by an en bloc method in which dolichol is added to the protein. O-linked glycosylation occurs in the Golgi (answer b) by a mechanism involving oligosaccharide (glycosyl) transferases rather than en bloc. N linked oligosaccharides are the most common oligo saccharides found in glycoproteins and contain sugar residues linked to the NH2 amide nitrogen of asparagine. 0linked oligosaccharides have sugar residues linked to hydroxyl groups on the side chains of serine and threonine and are less common than the N-linked species.