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Published on: July 27, 2016
Proteolytic processing and Ca2+-binding activity of dense-core vesicle polypeptides in Tetrahymena
1Department of Molecular Genetics & Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA.
Molecular Biology of the Cell
|April 4, 1998
Summary
Secretory vesicle core proteins undergo structural changes during assembly and release. Proteolytic processing and calcium exposure in Tetrahymena thermophila regulate these conformational shifts, offering insights into vesicle dynamics.
Area of Science:
- Cell biology
- Biochemistry
- Structural biology
Background:
- Dense-core secretory vesicles are crucial for cellular communication.
- Their formation and discharge involve complex protein rearrangements.
- The ciliate Tetrahymena thermophila provides a model system to study these processes.
Purpose of the Study:
- To investigate the mechanisms of dense-core secretory vesicle assembly and discharge.
- To identify regulatory factors controlling protein conformation within these vesicles.
- To explore the role of proteolytic processing and calcium in vesicle dynamics.
Main Methods:
- Proteolytic processing analysis of vesicle core proteins.
- In vitro calcium binding studies and sequence analysis.
- Chymotrypsin accessibility assays to assess protein conformational changes.
Main Results:
- Most vesicle core proteins originate from five precursors with conserved structural similarities despite low amino acid identity.
- Proteolytic processing sites are conserved, indicating involvement of specific proteases in core maturation.
- Proteolytic processing and calcium exposure induce sequential structural rearrangements in core proteins, influencing their folding.
Conclusions:
- Proteolytic processing and calcium are key regulators of dense-core vesicle assembly and postexocytic dispersal.
- Sequential conformational changes in core proteins underlie vesicle formation and rapid release.
- These mechanisms are likely conserved across different biological systems for organelle function.
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