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Home / Equine Research Bank / FEBS Lett / A novel Ca(2+)-dependent step in exocytosis subsequent to ve...
FEBS letters1995; 363(3); 217-220; doi: 10.1016/0014-5793(95)00318-4

A novel Ca(2+)-dependent step in exocytosis subsequent to vesicle fusion.

Abstract: Exocytosis begins with formation of a small fusion pore which then expands allowing rapid release of granular contents. We studied the influence of cytoplasmic free Ca2+ ([Ca2+]i) on the conductance of the initial pore and on the dynamics of subsequent expansion in horse eosinophils using the patch clamp technique. The mean initial conductance is approximately 200 pS independent of [Ca2+]i. This value is close to that previously found in beige mouse mast cells. The pore subsequently expands by 18 nS/s at [Ca2+]i < 10 nM, by 40 nS/s at [Ca2+]i = 1.5 microM and by 90 nS/s at [Ca2+]i = 10 microM. These results show that the structure of the initial fusion pore is independent of cytoplasmic Ca2+. However, the pore expansion is a Ca(2+)-dependent process modulating secretion at a step later than vesicle-plasma membrane fusion.
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Publication Date: 1995-04-24 PubMed ID: 7737405DOI: 10.1016/0014-5793(95)00318-4Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article presents a study on how cytoplasmic free calcium (Ca2+) influences the process of exocytosis, showing that while the initial fusion pore structure doesn’t rely on it, the pore expansion is a Ca2+-dependent process.

Research Background

  • Exocytosis is the process by which cells transport secretory products out through the plasma membrane. It begins with the creation of a small fusion pore which expands to allow the release of granular contents.
  • This study focuses on exploring how cytoplasmic free Ca2+ (intracellular levels of free calcium ions) influences the conductance of the initial pore and the dynamics of its subsequent expansion.

Research Methodology

  • The researchers employed the patch clamp technique, a widely used method in biology for measuring electric properties of cells, on horse eosinophils to study the aforementioned relationship.
  • The influence of various levels of [Ca2+]i (cytoplasmic free Ca2+) on the initial pore conductance and expansion rates were noted and compared.

Research Findings

  • The mean initial conductance was found to be nearly 200 pS, regardless of the [Ca2+]i levels. This indicates that the initial structure of the fusion pore is independent of cytoplasmic Ca2+.
  • The expansion rate of the pore was found to increase with increasing [Ca2+]i levels. At less than 10 nM [Ca2+]i, the rate was 18 nS/s, it increased to 40 nS/s at 1.5 µM [Ca2+]i, and further to 90 nS/s at 10 µM [Ca2+]i. This showed that the expansion of the pore after its initial formation is a Ca2+-dependent process.

Research Implications

  • The study concludes that the initial formation of the fusion pore during exocytosis isn’t influenced by intracellular calcium ion levels. However, the subsequent process of pore expansion prominently depends on Ca2+.
  • This implies that the level of cytoplasmic Ca2+ can modulate cell secretion by affecting the expansion of the fusion pore after the vesicle-plasma membrane fusion step.

Cite This Article

APA
Hartmann J, Lindau M. (1995). A novel Ca(2+)-dependent step in exocytosis subsequent to vesicle fusion. FEBS Lett, 363(3), 217-220. https://doi.org/10.1016/0014-5793(95)00318-4

Publication

FEBS letters
ISSN: 0014-5793
NlmUniqueID: 0155157
Country: England
Language: English
Volume: 363
Issue: 3
Pages: 217-220

Researcher Affiliations

Hartmann, J
  • Abt. Molekulare Zellforschung, Max-Planck-Institut für medizinische Forschung, Heidelberg, Germany.
Lindau, M

    MeSH Terms

    • Animals
    • Calcium / physiology
    • Cell Degranulation
    • Cytoplasm / physiology
    • Electric Conductivity
    • Eosinophils
    • Exocytosis
    • Horses
    • In Vitro Techniques
    • Membrane Fusion
    • Membrane Potentials
    • Patch-Clamp Techniques

    Citations

    This article has been cited 26 times.
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