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Journal Article

A novel Ca2+-dependent step in exocytosis subsequent to vesicle fusion.

MPS-Authors
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Lindau,  M.
Research Group of Nanoscale Cell Biology, MPI for Biophysical Chemistry, Max Planck Society;

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Citation

Hartmann, J., & Lindau, M. (1995). A novel Ca2+-dependent step in exocytosis subsequent to vesicle fusion. FEBS Letters, 363(3), 217-220. doi:10.1016/0014-5793(95)00318-4.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0028-1475-3
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 ∼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 μM and by 90 nS/s at [Ca2+]i = 10 μM. These results show that the structure of the initial fusion pore is independent of cytoplasmic Ca2+. However, the pore expansion is a Ca2+-dependent process modulating secretion at a step later than vesicle-plasma membrane fusion.