Changes in mobility of chromaffin granules in actin network with its assembly and Ca2+-dependent disassemby by gelsolin

S. Miyamoto, T. Funatsu, S. Ishiwata, S. Fujime

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15 Citations (Scopus)


As a final stage of cell signal transduction, secretory cells release hormones by exocytosis. Before secretory granules contact with the cell membrane for fusion, an actin-network barrier must dissociate as a prelude. To elucidate dynamical behaviors of secretory granules in actin networks, in vitro assembly and disassembly processes of actin networks were examined by means of dynamic light-scattering spectroscopy. We studied actin polymerization in the presence of chromaffin granules isolated from bovine adrenal medullas and found that the entanglement of actin filaments rapidly formed cages that confined granules in them. We also studied the effect of gelsolin, one of actin-severing proteins, on the network of actin filaments preformed in the presence of chromaffin granules. It turned out that the cages that confined granules rapidly disappeared when gelsolin was added in the presence of free Ca2+ ions. A semiquantitative analysis of dynamic light-scattering spectra permitted us to estimate the changes in the mobility (or the translational diffusion coefficient) of chromaffin granules in the actin network with its assembly and Ca2+-dependent disassembly by gelsolin. Based on the present results and some pieces of evidence in the literature, a model is proposed for biophysical situations before, during, and after an exocytotic event.

Original languageEnglish
Pages (from-to)1139-1149
Number of pages11
JournalBiophysical Journal
Issue number4
Publication statusPublished - 1993
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics


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