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Late events in regulated exocytosis
1Department of Physiology, University College London, UK.
Summary
Investigating intracellular mechanisms of exocytosis requires cell access via permeabilization or patch-pipettes. These methods allow controlled cytosol composition and reveal factors influencing exocytosis, like calcium ions and guanine nucleotides.
Area of Science:
- Cell Biology
- Molecular Mechanisms
- Membrane Trafficking
Background:
- Understanding exocytosis requires access to the cell interior.
- Plasma membrane permeabilization and patch-pipette application are key techniques.
- These methods allow manipulation of cytosol composition and study of soluble factors.
Purpose of the Study:
- To elucidate intracellular mechanisms controlling exocytosis.
- To investigate the roles of different permeabilization methods in studying exocytosis.
- To identify factors regulating the exocytotic machinery.
Main Methods:
- Plasma membrane permeabilization.
- Patch-clamp electrophysiology.
- Controlled manipulation of intracellular ion concentrations (e.g., Ca2+) and nucleotide levels.
Main Results:
- Different permeabilization techniques yield complementary data due to varying leakage extents.
- The exocytotic machinery can be activated by Ca2+ and/or guanine nucleotides.
- Evidence suggests involvement of guanine nucleotide-binding proteins (GP, GE) and Ca2+-binding proteins in some cell types.
Conclusions:
- Cellular access techniques are crucial for studying exocytosis regulation.
- Exocytosis can be triggered by Ca2+ and/or guanine nucleotides, with variations across cell types.
- ATP is not universally required for late-stage exocytosis.