Concanavalin A (Con A) covalently linked to Sepharose 4B beads induced localized degranulation of sensitized rat peritoneal mast cells in regions of contact between beads and cells. This degranulation was Ca2+ dependent and was not seen when sensitized mast cells bound to beads conjugated with a nonstimulating lectin, wheat germ agglutinin, or when unsensitized mast cells bound to Con A-Sepharose. The finding that sensitized mast cells which had adhered to Con A-Sepharose beads degranulated in regions of the cell away from the area of bead contact if exposed to soluble Con A excluded the possibility that the localized release was due to a redistribution of the IgE receptors or putative Ca2+ channels to the region of bead contact. The results suggest that, if an influx of Ca2+ is the mechanism for initiating mast cell degranulation, then the opening of Ca2+ channels in the plasma membrane of activated mast cells is a localized event and that Ca2+ acts locally within the cell to initiate exocytosis.
Localized mast cell degranulation induced by concanavalin A-sepharose beads. Implications for the Ca2+ hypothesis of stimulus-secretion coupling.
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D Lawson, C Fewtrell, M C Raff; Localized mast cell degranulation induced by concanavalin A-sepharose beads. Implications for the Ca2+ hypothesis of stimulus-secretion coupling.. J Cell Biol 1 November 1978; 79 (2): 394–400. doi: https://doi.org/10.1083/jcb.79.2.394
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