Lecture 08

• What is the sequence of events in clathrin-dependent endocytosis?

  Receptor binding, clathrin coat formation, vesicle budding

  
• How are receptor-ligand complexes processed inside a cell?

  They are sorted for recycling or degradation
• What are the three types of endocytosis mentioned?

  Phagocytosis, receptor-mediated endocytosis, pinocytosis

  
• What type of endocytosis is specific to specialised cells?

  Phagocytosis
• Which type of endocytosis is non-specific?

  Pinocytosis
• What are the key components of clathrin-coated pits?

  Receptor, adaptor protein, clathrin

  
• What is the role of the protein coat during vesicle formation?

  It shapes the vesicle and selects cargo

  
• What is scission in the context of vesicle formation?

  Pinching off a vesicle from a donor membrane
• Which protein plays a key role in vesicle fission?

  Dynamin

  
• How does dynamin function in vesicle scission?

  It cuts the membrane to release the vesicle

  
• What is the purpose of uncoating in vesicle transport?

  To allow fusion with the target membrane
• What is the role of auxilin in uncoating?

  It binds to clathrin lattices and disrupts interactions

  
• What happens to the clathrin coat after uncoating?

  It disassembles and the vesicle floats freely
• What is budding in the context of vesicle formation?

  Formation of small vesicles from donor membranes
• What are v-SNAREs?

  Integral membrane proteins on transport vesicles
• How do v-SNAREs interact with t-SNAREs?

  They initiate membrane fusion upon interaction

  
• What is the role of SNARE proteins in membrane fusion?

  They bring membranes together for fusion
• What is the process of SNARE disassembly?

  Involves NSF binding and ATP hydrolysis
• What is the major contributor to fluid uptake in cells?

  Clathrin-independent processes
• What are caveolae?

  Invaginations in the plasma membrane rich in lipids

  
• Where are caveolae frequently found?

  In fat cells like adipose tissue
• What happens after internalisation of vesicles?

  They fuse with early endosomes for processing
• What are the three primary endocytic pathways?

  Clathrin-coated pits, caveolin-coated pits, macropinocytosis

  
• What is the function of endosomes?

  Regulate transport of proteins and lipids
• What does low-density lipoprotein (LDL) deliver to cells?

  Cholesterol esters and phospholipids
• How does LDL interact with cells?

  Through cell surface receptors in clathrin-coated pits

  
• What happens to LDL in the lysosome?

  It is broken down into proteins, fatty acids, and cholesterol

  
• What does transferrin carry in the blood?

  Iron
• What occurs to transferrin in the endosome?

  It releases its bound iron due to lower pH

  
• What is transcytosis?

  Moving substances across a cell from one side to another
• Why is transcytosis necessary for large molecules?

  They cannot pass through tight junctions efficiently
• What elements are crucial for transcytosis?

  Energy, SNARE proteins, cytoskeletal elements
• What is the role of kinesin in transcytosis?

  Transporting vesicles along microtubule filaments
• What cells are specialised for phagocytosis?

  Macrophages and neutrophils
• What receptor do PAMs bind to?

  Toll-like receptor
• What occurs after recognition and adherence in phagocytosis?

  Engulfment occurs as the membrane surrounds the pathogen
• What happens when the phagosome fuses with a lysosome?

  Digestion of the engulfed material occurs
• What are the methods of endocytosis reviewed?

  • Phagocytosis
  • Receptor-mediated endocytosis
  • Pinocytosis
• What is the summary of clathrin-dependent endocytosis?

  • Sequence of events: receptor binding, clathrin coat formation, vesicle budding
  • Processing of receptor-ligand complexes: recycling or degradation
  • Examples in cell signalling context
• What are the different processing pathways after internalisation?

  • Recycling to plasma membrane
  • Degradation by lysosomal enzymes
  • Transcytosis