Several Factors Regulate Glycosylation of Glycoproteins
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Glycosylation of glycoproteins is regulated by several factors, including glycosyltransferase enzymes, suitable acceptor sites on proteins, Dol-P levels in tissues, and oligosaccharide-protein transferase activity. Different cells express different glycosyltransferases, and some require prior action of other enzymes. Glycosylation patterns can also differ between species and cells of the same species, influencing properties like the half-life of therapeutic proteins.
Several Factors Regulate Glycosylation of Glycoproteins
- 1. Several Factors Regulate Glycosylation of Glycoproteins
- 2. Glycosyltransferase Family Donor Substrate Fucosyltransferase GDP-Fucose Sialyltransferase CMP-Neuraminic acid Galactosyltransferase UDP-Galactose N-Acetyl glucosaminyl transferase UDP- N-Acetyl glucosamin N-Acetyl galactosaminyl transferase UDP- N-Acetyl galactosamin Mannosyltransferase GDP-Mannose Glucosyltransferase UDP-Glucose
- 3. Suitable acceptor sites in proteins. The tissue level of Dol-P. The activity of the oligosaccharide:protein transferase.
- 5. Different cells give different enzymes. Certain glycosyltransferases act only on the oligosaccaride chain if it has already been acted upon by another previous enzyme. EX: action of GlcNAc is important for Golgi alpha-mannosaidase. During which some genes are turned on & others are turned off.
- 6. Each enzyme has its own destination for insertion. Ex:HMG.CoA reductase ER membrane it may never encounter Golgi-located processing enzyme. Differences in proteins conformation may hinder access of proccessing enzymes.
- 7. The same cells(ex:fibroblast) of different species exhibit different patterns of processing enzymes. Species variation is an important factor which is used for production of Glycoproteins of Therapeutic use by Recombinant DNA tech. EX:synthesized Erythropoietin (EPO)
- 9. 1. Synthesized EPO is administered to patients with chronic anemia in order to stimulate Erythropoiesis. 2. The half-life of EPO in plasma is influenced by the nature of its glycosylation pattern. 3. Some species give patterns with short HL, others give them with normal HL.
- 11. 1 By lysosomal acid hydrolases. 2 They are Exo-enzymes. 3 If anyone is missing ,degradation cant complete>>>>Leading to diseases!