BIO 121 Lecture Notes - Lecture 10: Secretion, Amine, Mannose
23 Nov 2020
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Document Summary
Vessicles leaving the tgn have many destinations: Maturing lysosome (enz involved in intracellular digestion) Condensing secretory granules being released through regulated secretory pathway. Plasma membrane vesicles containing membrane proteins released to surface via constitutive secretory pathway (eg. surface antigens or cell coat proteins) Enzymes carrying out glycosylation are found in the lumen of er and golgi (not cytosol) Proteiins being glycosylated are likely bound for secretion or membrane proteins. Pre-fabricated oligosaccharide tree consisting of n-acetyl-glucosamine, several mannose and glucose residues are transferred from a lipid (dolichol) Dolichol and oligosaccharide complex is assembled on the cytosolic side of the er then flipped to the lumen (cisternal) side of the membrane by flippase. When tree is transferred the dolichol can be re-used by adding a new oligosaccharide tree for another round of glycosylation. Oligosaccharide tree is attached to asparagine in its free amino group (part of specific aa target sequence recognized by enzyme called oligosaccharide protein transferase)
