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The secretory granule matrix: a fast-acting smart polymer
1Department of Physiology and Biophysics, Mayo Clinic, Rochester, MN 55905.
Science (New York, N.Y.)
|February 12, 1993
Summary
The secretory granule matrix, a biopolymer, acts like an electrical diode. It swells with negative voltage and condenses with positive voltage, controlling product release during exocytosis.
Area of Science:
- Cell Biology
- Biophysics
- Biochemistry
Background:
- Secretory granule matrix is a charged polymer network involved in peptide and transmitter storage and release.
- Existing models of exocytotic fusion overlook the electrical properties of the secretory granule matrix.
Purpose of the Study:
- To investigate the electrical properties and voltage-dependent behavior of the secretory granule matrix.
- To determine the role of electrical potential gradients in controlling exocytotic decondensation and product release.
Main Methods:
- Applied electric fields to the secretory granule matrix.
- Measured matrix swelling, condensation, conductance, and pressure changes in response to voltage.
- Observed responses within milliseconds.
Main Results:
- The secretory granule matrix exhibited diode-like behavior, responding to negative voltages by swelling and increasing conductance.
- Positive voltages induced matrix condensation.
- Swollen matrix generated significant pressures (approx. 12 bar).
- Electrical responses occurred rapidly (milliseconds).
Conclusions:
- The secretory granule matrix possesses electrical properties, behaving akin to a diode.
- Potential gradients significantly influence matrix decondensation.
- Matrix decondensation, and consequently product release, is controlled by electrical potential gradients.