Essential Cell Biology

Transcription

1 Alberts Bray Hopkin Johnson Lewis Raff Roberts Walter Essential Cell Biology FOURTH EDITION Chapter 15 Intracellular Compartments and Protein Transport Copyright Garland Science 2014 CHAPTER CONTENTS MEMBRANE-ENCLOSED ORGANELLES PROTEIN SORTING VESICULAR TRANSPORT SECRETORY PATHWAYS (ENDOCYTIC PATHWAYS, ei käydä läpi tässä) 1

2 MEMBRANE-ENCLOSED ORGANELLES Eukaryotic Cells Contain a Basic Set of Membrane-enclosed Organelles Membrane-enclosed Organelles Evolved in Different Ways 2

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4 PROTEIN SORTING Proteins Are Transported into Organelles by Three Mechanisms Signal Sequences Direct Proteins to the Correct Compartment Proteins Enter the Nucleus Through Nuclear Pores Proteins Unfold to Enter Mitochondria and Chloroplasts Proteins Enter Peroxisomes from Both the Cytosol and the Endoplasmic Reticulum Active and/or passive particle transport? 4

5 PROTEIN SORTING Proteins Are Transported into Organelles by Three Mechanisms Signal Sequences Direct Proteins to the Correct Compartment Proteins Enter the Nucleus Through Nuclear Pores Proteins Unfold to Enter Mitochondria and Chloroplasts Proteins Enter Peroxisomes from Both the Cytosol and the Endoplasmic Reticulum 5

6 Recombinant DNA techniques to study signal sequences PROTEIN SORTING Proteins Are Transported into Organelles by Three Mechanisms Signal Sequences Direct Proteins to the Correct Compartment Proteins Enter the Nucleus Through Nuclear Pores Proteins Unfold to Enter Mitochondria and Chloroplasts Proteins Enter Peroxisomes from Both the Cytosol and the Endoplasmic Reticulum 6

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10 PROTEIN SORTING Proteins Are Transported into Organelles by Three Mechanisms Signal Sequences Direct Proteins to the Correct Compartment Proteins Enter the Nucleus Through Nuclear Pores Proteins Unfold to Enter Mitochondria and Chloroplasts Proteins Enter Peroxisomes from Both the Cytosol and the Endoplasmic Reticulum 10

11 PROTEIN SORTING Proteins Enter the Endoplasmic Reticulum While Being Synthesized Soluble Proteins Made on the ER Are Released into the ER Lumen Start and Stop Signals Determine the Arrangement of a Transmembrane Protein in the Lipid Bilayer 11

12 Dog s pancreas, produces and secretes large amounts of digestive enzymes 12

13 PROTEIN SORTING Proteins Enter the Endoplasmic Reticulum While Being Synthesized Soluble Proteins Made on the ER Are Released into the ER Lumen Start and Stop Signals Determine the Arrangement of a Transmembrane Protein in the Lipid Bilayer 13

14 PROTEIN SORTING Proteins Enter the Endoplasmic Reticulum While Being Synthesized Soluble Proteins Made on the ER Are Released into the ER Lumen Start and Stop Signals Determine the Arrangement of a Transmembrane Protein in the Lipid Bilayer 14

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16 VESICULAR TRANSPORT Transport Vesicles Carry Soluble Proteins and Membrane Between Compartments Vesicle Budding Is Driven by the Assembly of a Protein Coat Vesicle Docking Depends on Tethers and SNAREs 16

17 SECRETORY PATHWAYS Most Proteins Are Covalently Modified in the ER Exit from the ER Is Controlled to Ensure Protein Quality The Size of the ER Is Controlled by the Demand for Protein Proteins Are Further Modified and Sorted in the Golgi Apparatus Secretory Proteins Are Released from the Cell by Exocytosis Many proteins are glycosylated on asparagines in the ER 17

18 SECRETORY PATHWAYS Most Proteins Are Covalently Modified in the ER Exit from the ER Is Controlled to Ensure Protein Quality The Size of the ER Is Controlled by the Demand for Protein Proteins Are Further Modified and Sorted in the Golgi Apparatus Secretory Proteins Are Released from the Cell by Exocytosis Chaperones help the proteins to fold correctly but also prevent misfolded or partially assembled proteins from leaving the ER 18

19 SECRETORY PATHWAYS Most Proteins Are Covalently Modified in the ER Exit from the ER Is Controlled to Ensure Protein Quality The Size of the ER Is Controlled by the Demand for Protein Proteins Are Further Modified and Sorted in the Golgi Apparatus Secretory Proteins Are Released from the Cell by Exocytosis Unfolded protein response, UPR 19

20 SECRETORY PATHWAYS Most Proteins Are Covalently Modified in the ER Exit from the ER Is Controlled to Ensure Protein Quality The Size of the ER Is Controlled by the Demand for Protein Proteins Are Further Modified and Sorted in the Golgi Apparatus Secretory Proteins Are Released from the Cell by Exocytosis 20

21 Golgi apparatus = dictyosome in plant cells (diktyosomi kasvisoluissa) SECRETORY PATHWAYS Most Proteins Are Covalently Modified in the ER Exit from the ER Is Controlled to Ensure Protein Quality The Size of the ER Is Controlled by the Demand for Protein Proteins Are Further Modified and Sorted in the Golgi Apparatus Secretory Proteins Are Released from the Cell by Exocytosis 21

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23 ENDOCYTIC PATHWAYS Specialized Phagocytic Cells Ingest Large Particles 23