Calcium Promotes the Formation of Syntaxin 1 Mesoscale Domains through Phosphatidylinositol 4,5-Bisphosphate
SourceJournal of Biological Chemistry, 291, 15, (2016), pp. 7868-7876
Article / Letter to editor
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Journal of Biological Chemistry
SubjectRadboudumc 2: Cancer development and immune defence RIMLS: Radboud Institute for Molecular Life Sciences
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P-2) is a minor component of total plasma membrane lipids, but it has a substantial role in the regulation of many cellular functions, including exo- and endocytosis. Recently, it was shown that PI(4,5)P-2 and syntaxin 1, a SNARE protein that catalyzes regulated exocytosis, form domains in the plasma membrane that constitute recognition sites for vesicle docking. Also, calcium was shown to promote syntaxin 1 clustering in the plasma membrane, but the molecular mechanism was unknown. Here, using a combination of superresolution stimulated emission depletion microscopy, FRET, and atomic force microscopy, we show that Ca2+ acts as a charge bridge that specifically and reversibly connects multiple syntaxin 1/PI(4,5)P-2 complexes into larger mesoscale domains. This transient reorganization of the plasma membrane by physiological Ca2+ concentrations is likely to be important for Ca2+-regulated secretion.
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