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Lecture 6

Second Section Lecture 6


Department
Biology
Course Code
BIO130H1
Professor
Jane Mitchell
Lecture
6

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Lecture 6 Mar. 15/12
Intracellular Compartments and Protein Sorting
Transmembrane protein secretion path
Cytosol ER Golgi Secretory Vesicle Plasma Membrane (PM)/Exocytosis
Golgi apparatus
Glycosylates proteins and lipids
Glycosylation: addition of glycans (carbohydrate) to organic molecules
Cis face faces ER
Trans face faces PM
Protein glycosylation
Begins in ER, single type of oligosaccharide attached to protein
Oligosaccharide modification occurs in Golgi
Modifications occurs in lumen of organelles
Maintenance of membrane protein asymmetry
Each protein inserted into ER in specific orientation
Protein asymmetry in ER insertion is maintained throughout transport process
Protein side that faces cytosol always faces cytosol
Protein side that faces lumen always faces lumen, extracellular fluid at PM
Detergents/other removal processes can change protein facing orientation
Endosomes
Membrane bound organelle
Carries materials newly ingested by endocytosis
Passes material to lysosomes for degradation
Lysosomes
Sac of digestive enzymes, that are delivered as vesicles ER/Golgi
Degrade various materials received from endosomes
Lysosomes can fuse with endosomes to form endolysosome
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