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Sorting within the regulated secretory pathway occurs in the trans-Golgi network
W S Sossin1, J M Fisher, R H Scheller
1Department of Biological Sciences, Stanford University, California 94305.
The Journal of Cell Biology
|January 1, 1990
Summary
Bioactive peptides from a common precursor are sorted into different vesicles in Aplysia bag cell neurons. Protein trafficking controls peptide levels and localization, enabling regulated release of active molecules.
Area of Science:
- Neurobiology
- Cell Biology
- Molecular Biology
Background:
- Aplysia bag cell neurons synthesize egg-laying hormone precursor, a source of bioactive peptides.
- Prohormone processing involves sequential cleavages and sorting into distinct dense core vesicle (DCV) classes.
Purpose of the Study:
- To investigate the mechanisms of prohormone sorting and processing in Aplysia bag cell neurons.
- To understand how protein trafficking regulates the localization and release of bioactive peptides.
Main Methods:
- Utilized monensin treatment to differentiate stages of prohormone cleavage.
- Analyzed prohormone intermediate sorting in the trans-Golgi network.
- Observed differential turnover and transport of distinct DCV classes.
Main Results:
- Prohormone processing occurs in two stages: an early Golgi cleavage and later DCV-dependent cleavages.
- Prohormone intermediates are sorted within the trans-Golgi network.
- Large soma-specific DCVs undergo turnover, while small DCVs are transported for regulated release.
Conclusions:
- Protein trafficking plays a critical role in differentially regulating the levels and localization of bioactive peptides derived from a single prohormone.
- Distinct DCV classes are formed and utilized differently, impacting peptide availability and release.
- This sorting mechanism ensures the targeted delivery and regulated secretion of specific neuropeptides.