Zh. Guo et al., RELOCATION OF THE T-SNARE SNAP-23 FROM LAMELLIPODIA-LIKE CELL-SURFACEPROJECTIONS REGULATES COMPOUND EXOCYTOSIS IN MAST-CELLS, Cell (Cambridge), 94(4), 1998, pp. 537-548
For regulated secretion, mast cells and several other cell types utili
ze compound exocytosis, a combination of granule-plasma membrane and g
ranule-granule fusions. The molecular machinery that controls this mas
sive export process has not been identified. We report that SNAP-23, a
t-SNARE related to SNAP-25, relocates in response to stimulation from
plasma membrane lamellipodia-like projections to granule membranes in
permeabilized mast cells. While relocation is a prerequisite for secr
etion, it can occur without membrane fusion and will expedite a subseq
uent secretory response. After relocation, SNAP-23 is required for exo
cytosis, implying a crucial role in promoting membrane fusion. Thus, r
elocation of this SNARE regulates compound exocytosis and links granul
e-plasma membrane and granule-granule fusions.