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Mechanisms of signal transduction in photo‐stimulated secretion in Phaeocystis globosa
Author(s) -
Quesada Ivan,
Chin Wei-Chun,
Verdugo Pedro
Publication year - 2006
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2006.02.081
Subject(s) - exocytosis , cytosol , biophysics , secretion , chemistry , intracellular , granule (geology) , microbiology and biotechnology , biology , biochemistry , enzyme , paleontology
Phaeocystis globosa , a leading agent in marine carbon cycling, releases its photosynthesized biopolymers via regulated exocytosis. Release is elicited by blue light and relayed by a characteristic cytosolic Ca 2+ signal. However, the source of Ca 2+ in these cells has not been established. The present studies indicate that Phaeocystis ’ secretory granules work as an intracellular Ca 2+ oscillator. Optical tomography reveals that photo‐stimulation induces InsP 3 ‐triggered periodic lumenal [Ca 2+ ] oscillations in the granule and corresponding out‐of‐phase cytosolic oscillations of [Ca 2+ ] that trigger exocytosis. This Ca 2+ dynamics results from an interplay between the intragranular polyanionic matrix, and two Ca 2+ ‐sensitive ion channels located on the granule membrane: an InsP 3 ‐receptor‐Ca 2+ channel, and an apamin‐sensitive K + channel.