Glycoproteins
Start with the big picture
Glycoprotein glycans are attached mainly through N-linked or O-linked bonds. N-linked glycans are assembled on dolichol phosphate in the rough ER, transferred to asparagine in a suitable sequence, and processed in the Golgi into high-mannose, hybrid, or complex forms. O-linked glycans are added sequentially to serine, threonine, or hydroxyproline, without a common core. Terminal sialic acid can affect charge and serum half-life; its removal exposes galactose and promotes hepatic clearance. Glycans also support protein quality control, cell adhesion, immune recognition, and trafficking. The topic distinguishes mucins and proteoglycans from glycoproteins and introduces lysosomal degradation, I-cell disease, congenital disorders of glycosylation, and analytical tools.
What you'll learn
- Distinguish N-linked from O-linked glycosylation by attachment site and processing.
- Describe the core N-linked glycan and its ER-to-Golgi processing.
- Explain how terminal sialic acid relates to glycoprotein clearance.
- Identify roles of lectins, mucins, and glycan structures in recognition and function.
- Recognize the glycan-processing defects associated with I-cell disease and CDG.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
