Protein Glycosylation is the reaction in that a carbohydrate, example for a glycosyl donor that is attached to a hydroxyl or other functional set of another molecule a glycosyl acceptor. In the biology glycosylation says to the enzymatic process which attaches glycans to lipids, proteins or other organic molecules. This enzymatic process produces one of the fundamental biopolymers establish in cells along with DNA, RNA and proteins. Glycosylation is the form of co-translational and post-translational modification. Glycans serve a various of functional and structural roles in membrane and secreted proteins. The popularity of proteins synthesized in the rough ER undergo glycosylation. It is an enzyme-directed site-specific process, as opposed to the non-enzymatic chemical reaction of glycation. The Glycosylation is also there in the cytoplasm and nucleus as the O-GlcNAc modification.