Figure 4.

Exocytosis is independent of NSF, but it is inhibited by α-SNAP. All experiments were performed as in Figure 2D, with ATP present in the preincubation and triggering phase and Ca²⁺ added during the triggering phase. All other additions were present only in the preincubation phase. (A) Preincubation of membrane sheets with 1 mM NEM does not inhibit exocytosis. (B and C) Preincubation with 2 μM α-SNAP (wt) or α-SNAP^L294A (mut) inhibits Ca²⁺-dependent exocytosis. Inhibition by wild-type but not mutant α-SNAP is prevented by the inclusion of either RBC (B) or purified NSF (C). Values are given as mean ± SEM (n = 9–18 membrane sheets for each condition).