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Preparation of Synaptic Plasma Membrane and Postsynaptic Density Proteins Using a Discontinuous Sucrose Gradient
Published on: September 3, 2014
Syntaxin6 separates from GM1a-rich membrane microdomain during granule maturation
Osamu Katsumata1, Junko Fujita-Yoshigaki, Miki Hara-Yokoyama
1Department of Physiology and Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho-Nishi, Matsudo, Chiba 271-8587, Japan.
Biochemical and Biophysical Research Communications
|April 27, 2007
Summary
Secretory granule (SG) maturation involves dynamic changes. Syntaxin6 and VAMP4 associate with GM1a-rich membranes during formation but separate during maturation in rat parotid acinar cells.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Secretory granules (SGs) in rat parotid acinar cells exhibit compositional differences between immature (ISGs) and mature (MSGs) stages.
- This suggests dynamic changes in SG components during granule maturation.
Purpose of the Study:
- To investigate the molecular mechanisms underlying secretory granule maturation.
- To identify changes in membrane microdomains during the transition from immature to mature secretory granules.
Main Methods:
- Purification of secretory granules (SGs) from rat parotid glands.
- Separation of low-density detergent-resistant membrane fractions (DRMs) from SGs and ISGs.
- Analysis of protein and lipid composition within DRMs using biochemical assays.
- Induction of ISG formation using isoproterenol injection in rats.
Main Results:
- Syntaxin6 and VAMP4 were found in distinct DRMs from mature SGs, separate from GM1a-rich DRMs containing VAMP2.
- Immature SGs (ISGs), enriched by isoproterenol treatment, showed higher concentrations of syntaxin6, VAMP4, and gamma-adaptin.
- DRMs from ISGs contained GM1a, syntaxin6, VAMP4, and VAMP2 together, indicating a different membrane microdomain composition compared to mature SGs.
Conclusions:
- Syntaxin6 and VAMP4 associate with GM1a-rich membrane microdomains during the formation of secretory granules.
- These proteins likely enter distinct membrane microdomains before their removal from granules during the maturation process.
- The findings provide insights into the dynamic membrane remodeling occurring during secretory granule maturation.
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