Lawson D, Fewtrell C, Raff M C
J Cell Biol. 1978 Nov;79(2 Pt 1):394-400. doi: 10.1083/jcb.79.2.394.
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.
与琼脂糖4B珠共价连接的伴刀豆球蛋白A（Con A）可诱导致敏大鼠腹膜肥大细胞在珠与细胞接触区域发生局部脱颗粒。这种脱颗粒依赖于Ca2+，当致敏肥大细胞与结合了非刺激性凝集素麦胚凝集素的珠结合时，或者当未致敏肥大细胞与Con A - 琼脂糖结合时，均未观察到这种脱颗粒现象。如果将附着在Con A - 琼脂糖珠上的致敏肥大细胞暴露于可溶性Con A，这些细胞会在远离珠接触区域的细胞部位脱颗粒，这一发现排除了局部释放是由于IgE受体或假定的Ca2+通道重新分布到珠接触区域的可能性。结果表明，如果Ca2+内流是引发肥大细胞脱颗粒的机制，那么活化肥大细胞质膜中Ca2+通道的开放是一个局部事件，并且Ca2+在细胞内局部起作用以启动胞吐作用。
