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Chapter 13

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Chapter 13

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  1. Chapter 13 • Intracellular Vesicular Traffic 張學偉 助理教授

  2. The molecular mechanisms of membrane transport and the maintenance of compartmental diversity


  4. There are various types of coated vesicles Mediate transport from Golgi & from plasma membrane Mediate transport from ER & Golgi Each type is used for different transport steps in the cell.

  5. The assembly of a clathrin coat drives vesicle formation

  6. by charperone (hsp70) Major coat protein: clathrin & adaptin There are at least four types of adaptins, each specific for a different set of cargo receptor.

  7. Both the pinching-off and uncoating of coated vesicles are regulated processes

  8. Not all transport vesicles are spherical  Various size & shape

  9. Monomeric GTPase control coat assembly

  10. SNARE proteins and targeting GTPases guide membrane transport

  11. Trans-SNARE complex

  12. Interacting SNAREs need to be pried apart before they can function again cytosol Cycle

  13. Rab proteins (monomeric GTPase) help ensure the specificity of vesicle docking

  14. Rab facilitate docking of transport vescicles. Rab &its effector Structure vary greatly Function common (1.concentrate & tether vesicle near target site 2. Trigger release of SNARP control protein) cycle

  15. SNARE may mediate membrane fusion Process for SNARE concentrate in membrane fusion

  16. Viral fusion proteins and SNAREs may use similar strategies

  17. Transport from the ER through the golgi apparatus

  18. ER exit site 50nm vesicle > 200 mem protein Cargo Recruitment

  19. Only proteins that are properly folded and assembled can leave the ER Incomplete ER resident protein

  20. CF (Cystic fibrosis) Defect in Cl- transport This is not because the mutation inactivated the protein, But because the active protein is discarded before it reaches the plasma membrane.

  21. Transport from the ER to the Golgi apparatus is mediated by vesicular tubular clusters. Heterotypic fusion Homotypic memb fusion is not restricted to form VTC.

  22. The structure formed when ER-derived vesicles fuse with one another are called.

  23. ER retrival signal

  24. The retrieval pathway to the ER uses sorting signals Lys-Asp-Glu-Leu (KDEL) Short retrieval signal at c-terminal Resident ER membrane protein KKXX at c-terminal end  direct interact with COPI coat

  25. Many proteins are selectively retained in the compartments in which they function Aggregation of proteins that function in the same compartment - called kin recognition

  26. The golgi apparatus consists of an ordered series of compartments.

  27. Two major classes of N-linked oligosaccharide complex High mannose No new sugar added in Golgi

  28. Oligosaccharide processing in ER and Golgi

  29. High specific endoglycosidase Can distinguish between these two type

  30. Proteoglycans are assembled in the Golgi Apparatus O-linked glycosylation Proteoglycans are secreted or anchored to plasma membrane

  31. 1. N-linked is prevalent in all eukaryotes, but absent in procaryotes. 2. limited flexibility. 3. Recognition 4. Regulation of development 5. Protective coat unit 6. Cell-cell adhesion What is the purpose of N-glycosylation?

  32. N-linked

  33. The golgi cisternae are organized as a series of processing compartments

  34. Functional compartmentalization

  35. Matrix proteins form a dynamic scaffold that helps organize the apparatus