Biology 2382B Lecture 6: Lecture 6- Receptor mediated endoytosis
21 Apr 2016
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Delivery of membrane and cytosolic proteins for degradation in lysosomes. Cells: how to internalize extracellular materials: phagocytosis. Only possible for specialized cells, not all cells can do this. When specialized cells engulf solid particles to form internal vesicles (phagosomes: pinocytosis. When specialized cells brings in small vesicles containing extracellular fluids: receptor-mediated endocytosis. A method of selective internalization of specific ligands via receptors. Used to bring hormones (e. g. insulin), glycoproteins, sugars into cells. Two examples: ldl (brings in lipid) and transferrin (brings in iron) Low-density lipoprotein (ldl: lipids are transported in large well-defined water soluble complexes/ particles called lipoproteins, ldl structure: Has an amphipathic shell which is composed of 1) phospholipid monolayer and: apolipoprotein. Clathrin/ ap-coated vesicles: two-layer coat: clathrin and adapter protein (ap) complexes. Ap2-pm (at plasma membrane: ap complexes recognize sorting signals of cargo proteins or receptors. 3 ph-dependent binding of ldl particles to the ldl receptor: ldl receptor has three domains:
