Receptor-Mediated Endocytosis

1. Receptor-Mediated Endocytosis Zhong huan zi

2. Endocytosis Bulk-phase endocytosis Receptor-mediated endocytosis Receptor mediated endocytosis is a process by which cells internalize molecules or viruses. As its name implies, it depends on the interaction of that molecule with a specific binding protein in the cell membrane called a receptor. RME provides a means for the macromolecules that may be at relatively low concentrations in the extracellular fluid.

3. RME and Coated pits Formation of Coated vesicles: The plasma membrane form a pit. The pit is lined with receptor protiens that have picked up particular molecules from the surroundings. The pit will pinch closed to form a vesicle that will carry the molecules into the cytoplasm.

4. Coated pitsCoated vesicles

5. Coatedvesicles clathrin

6. Coated vesicles fomation • Coated vesicles: • Clathrin • Receptor _ligand complex • Adaptor /adaptin AP2/ 1/ 3 GTPase

9. The whole process of Receptor-Mediated Endocytosis

11. What types of ligands enter by RME? • Toxins and lectins • Viruses • Serum transport proteins and antibodies eg: Transferrin Low density lipoprotein Transcobalamin Yolk proteins IgE Polymeric IgA • Hormones and Growth Factors

12. Experimental pathways… Embryonic development Question:How are the high-molecular-weight yolk protein able to enter the oocyte? the discovery coated pits Postulated: the yolk protein were specifically adsorbed onto the outer surface of the membrane of the coated pits ,which would then invaginate(内化)as coated vesicles。 Experiment Envidence(1969 Toku kanaaseki ken kadota Osaka) (1975 B.P Cambridge solubilized and fractionated yolk protein by SDS-PAGE)

13. Experimental pathways… • FH : familial hypercholesterolermia 家族性血胆脂醇过多症 LDL adisease by atheroscleroticplaque （动脉粥样蚀斑） because the accumulate of LDL in cells and ECM 动脉粥样蚀斑的形成

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