Fig. 2.

Regulation of lytic granule exocytosis. CD16 signals for co-localization of Munc13-4 to perforin granules, while LFA-1 signals for co-localization of Rab27a to perforin granules. Mature granules at the immune synapse are positive for Munc13-4 and Rab27a. Rab27a has multiple effectors during exocytosis, including Munc13-4 and Slp1 and/or Slp2. Unknown SNARE complexes mediate these fusion events, and Stx11 and Munc18-2, which interact directly, are required for exocytosis at an unknown stage