Trimming and fuher modification of N-linked glycoproteins takes place at

Ans: a) Golgi apparatus N-Glycosylation begins in the ER and completed in Golgi. Trimming and fuher addition of sugars take place in Golgi. There are 3 types of N-glycosylation. 1. High-mannose type 2. Complex type 3. Hybrid type To form high-mannose chains, the glucose and some of the peripheral mannose residues are removed by glycosidases in Golgi. To form complex type, the glucose residues and four of the mannose residues are removed by glycosidases in the endoplasmic reticulum and Golgi, then N-acetyl glucosamine, galactose, and N-Acetylneuraminic acid are added in reactions catalyzed by glycosyltransferases in the Golgi apparatus. Hybrid chains are formed by paial processing, forming complex chains on one arm and mannose units on the other arm.