Endocytosis

Kinetics
6. Dual Role of Sialic Acid
7. Receptor Distribution and Topology
8. Avian Hepatic Binding Protein
9. Perspectives
- References
4. The Structure of Clathrin-Coated Membranes: Assembly and Disassembly
1. Introduction
1.1. Coated Membranes in Cells
1.2. Isolated Coated Vesicles
2. Isolation, Extraction, and Fractionation of Coated Vesicles and Their Components
2.1. Purification of Coated Vesicles
2.2. Release of Coats from Vesicles
2.3. Fractionation of Coated Vesicle Extracts
3. Composition of Coated Vesicles
3.1. Clathrin Triskelions
3.1.1. Clathrin Triskelions: The Structural and Functional Unit
3.1.2. Clathrin Triskelions: Composition
3.1.3. Clathrin Triskelions: The Heavy Chain
3.1.4. Clathrin Triskelions: Light Chains
3.1.5. Clathrin Triskelions: Heavy-Chain-Light-Chain Interactions
3.2. Assembly Polypeptides
3.3. Tubulin and ?-Related Polypeptides
3.4. Calmodulin
3.5. Lipid and Carbohydrate
4. Clathrin Coat Dynamics
4.1. Assays for Coat Assembly
4.1.1. Electron Microscopy
4.1.2. Sedimentation Assays
4.1.3. Light Scattering
4.2. Coat Assembly: Triskelions
4.2.1. Coat Assembly: Clathrin Domains Required
4.3. Coat Reassembly: Role of Assembly Polypeptides
4.4. Coat Assembly: Clathrin Binding to Membranes
4.5. Coat Disassembly
5. Conclusions
- References
5. Transferrin: Receptor-Mediated Endocytosis and Iron Delivery
1. Introduction
2. Structure of Transferrin
2.1. Chemical Characterization
2.2. Carbohydrate Chains
2.3. Iron Binding
2.4. Iron Release
3. Function of Transferrin
3.1. Ubiquity of Transferrin Receptors
3.2. Transferrin-Reticulocyte Interactions
4. Role of Transferrin in Biology and Medicine
4.1. Requirements for Cell Growth and Proliferation
4.2. Relationship to Malignant Transformation

4 3 Immunological Surveillance of Cancer and the Transferrin Receptor
4.4. Use of the Transferrin Receptor in Chemotherapy
5. The Transferrin Receptor: Biochemical Characterization
5.1. Transferrin Receptor Structure
5.2. Transferrin Receptor Biosynthesis
6. Cellular Binding and Uptake of Transferrin: Kinetic and Inhibitor Studies
7. Prelysosomal Divergence of EGF and Transferrin During Endocytosis
7.1. Characterization of Binding Sites for EGF and Transferrin
7.2. Release and Degradation of EGF and Transferrin from Cells at 37°C
7.3. Density Gradient Centrifugation of Cell Fractions on Colloidal Silica
7.4. Fluorescence Microscopy
7.5. Electron Microscopy
8. Role of a Prelysosomal Compartment in Transferrin-Bound Iron Release and Receptor-Bound Ligand Release
9. Biosynthesis and Recycling of Receptors: Two Roles for Secretion in Endocytosis?
10. Summary and Future Prospects
- References
6. POLYMERIC IgA AND GALACTOSE-SPECIFIC PATHWAYS IN RAT HEPATOCYTES: EVIDENCE FOR INTRACELLULAR LIGAND SORTING
1. Introduction
2. Receptor-Mediated Endocytosis in Rat Hepatocytes
2.1. Diversity of Recognition Systems
2.2. Diversity of the Fates of Ligands and Receptors
3. Methodology
3.1. Tagging of Ligands and Double-Labeling Experiments
3.2. Assessment of Polymeric IgA Derivatives
3.3. Assessment of Galactose-Exposing Derivatives
3.4. Independence of Ligand Processing
4. Fate of Secretory Component and Galactose-Specific Receptors
4.1. Biosynthesis and Properties of the Secretory Component
4.2. Endocytosis of Secretory Component and Postendocytotic Events
4.3. Properties of the Galactose-Specific Receptors
4.4. Endocytosis of Galactose-Specific Receptors and Postendocytotic Events
5. Pathways of Polymeric IgA and of Galactose-Exposing Derivatives in Rat Hepatocytes: Ultrastructural Studies
5.1. The Polymeric IgA-Specific Pathway
5.2. The Galactose-Specific Pathway
5.3. Cointernalization of Polymeric IgA and Galactose-Exposing Derivatives
6. Intracellular Ligand Sorting in Rat Hepatocytes
6.1. The DAB-Induced Density Shift
6.2. Concomitant Density Shift of Ligands
6.3. Combined Differential and Isopycnic Centrifugation Studies
7. Mechanism of Ligand and Receptor Sorting
7.1. Acidification Mediates a Two-Phase Partition
7.2. Phase Sorting
7.3. Receptor Sorting and Specific Addressing
7.4. Current Model and Implications
8. Properties of Ligand-Sorting Organelles
8.1. Physical and Morphological Properties
8.2. Membrane Composition
8.3. Absence of Proteolysis
8.4. Cholesterol-Rich Membrane
9. Conclusions and Perspectives
9.1. Identification of Sorting Organelles
9.2. Perspectives on the Sorting Mechanism
9.3. Ligand-Containing Structures as Transient or Stable Organelles
- References
7. Toxins
1. Introduction
2. Toxin Structure
2.1. The Plant Lectins Ricin, Abrin, Modeccin, and Viscumin
2.2. Diphtheria Toxin and Pseudomonas aeruginosa Exotoxin A
2.3. Cholera Toxin, E. coli Heat-Labile Toxin, Pertussis Toxin, and Shigella Toxin
2.4. Toxin Conjugates
3. Intracellular Action
3.1. Diphtheria Toxin and Pseudomonas Toxin
3.2. Ricin, Abrin, Modeccin, Viscumin and Shigella Toxin
3.3. Cholera Toxin, E. coli Heat-Labile Toxin, and Pertussis Toxin
3.4. Anthrax Toxin
4. Function of the Cell Surface Binding Sites
4.1. Characterization of the Binding Sites
4.1.1. Binding Sites for Ricin, Abrin, Modeccin, and Viscumin
4.1.2. Diphtheria Toxin Receptor
4.1.3. Receptor for Cholera Toxin and E. coli Toxin
4.1.4. Binding Sites for Other Toxins
4.2. Characteristics of the Binding
4.3. Ability of Binding Sites to Facilitate Toxin Entry
5. Endocytosis and Transport of Toxin-Containing Vesicles
5.1. Morphological Studies
5.2. Importance of Endocytosis
5.3. Intracellular Transport of Toxin-Containing Vesicles
5.4. Properties of Vesicular Compartments Relevant to Toxin Entry
6. Requirements for Toxin Exit from Intracellular Vesicles
6.1. Role of Low pH
6.1.1. Penetration of Diphtheria Toxin at Low pH
6.1.2. Requirement for Low pH for Entry of Other Toxins
6.1.3. Other pH Effects on Toxin Entry
6.2. Ion Requirements
6.2.1. Role of Calcium
6.2.2. Role of Chloride
6.3. Energy Requirements
6.4. Role of the Disulfide Bond
6.5. Studies of Toxin Entry Using Photoreactive Compounds
7. Conclusions
- References
8. Acidification of Endocytic Vesicles and Lysosomes
1. Introduction
1.1. Historical Background
1.2. Acidification in Various Cell Types
2. Measurement of pH
2.1 Definition of pH and Principles of Measurement
2.2 Donnan Effects
2.3 Methods for the Measurement of pH within Endocytic Vesicles and Lysosomes
2.3.1. Distribution of Weak Bases
2.3.2. Spectroscopic Methods
2.3.3. Other Methods
3. Lysosomal pH
3.1. Perturbation of Lysosomal pH
3.2. Role of Lysosome Acidification
4. Endocytic Vesicle pH
4.1. Consequences of Endocytic Vesicle Acidification
4.1.1. Receptor Recycling
4.1.2. Iron Release from Transferrin
4.1.3. Cytoplasmic Penetration by Viruses
4.1.4. Diphtheria Toxin Penetration
4.1.5. Summary of Biological Effects
5. Mechanism of Acidification
6. Summary
- References
9. Mathematical Modeling of Receptor-Mediated Endocytosis
1. Introduction
2. General Considerations of the Endocytic Pathway
2.1. Binding and Internalization
2.2. Ligand Degradation and Receptor Reutilization
3. General Models of the Endocytosis of Asialoglycoproteins
4. Surface Events and Internalization
4.1. The Interaction of Receptors with Coated Pits
4.2. The Interaction of Ligands with Receptors
- References
10. Morphologic Methods in the Study of Endocytosis in Cultured Cells
1. Introduction
2. Cytochemical Markers
2.1. Antibodies to Ligands and Receptors
2.2. Ligand Conjugates to Fluorochromes
2.3. Ligand Conjugates to Electron Microscopic Markers
2.3.1. Horseradish Peroxidase
2.3.2. Ferritin
2.3.3. Colloidal Gold
3. Light Microscopic Fluorescence and Image Intensification Methods
4. Electron Microscopic Morphologic Methods
4.1. Direct Embedding Technique for Cultured Cells
4.2. Membrane Contrast Enhancement Techniques
4.3. Serial Section Techniques
4.4. Stereo Analysis of Thin Sections

5 Immunocytochemistry
5.1. Light Microscopic Fluorescence
5.2. Electron Microscopic Immunocytochemical Methods
5.2.1. General Approaches
5.2.2. EGS and GBS Fixation and Processing Methods
5.2.3. Horseradish Peroxidase Labeling
5.2.4. Ferritin Bridge Labeling
6. Direct Mechanical Microinjection Methods
7. Experimental Protocols for the Study of Endocytosis
- References