Figure 4.

PIP₂ slows the disassembly kinetics of C2AB–Ca²⁺–liposome complexes containing Doc2β but not syt1. A, schematic of disassembly assay. C2AB–Ca²⁺–liposome complexes were preassembled and then rapidly mixed with EGTA while monitoring FRET between tryptophan residues in C2AB and dansyl-PE acceptors on the liposomes. B, representative traces (left) and rate constants derived from single-exponential fits (right) for disassembly of Doc2β–Ca²⁺–membrane complexes. The inclusion of 1 mol % PIP₂ in liposomes containing 15% PS slowed the observed rates of disassembly by ∼10-fold. C, as above but for syt1 C2AB. In contrast to the case of Doc2β, membrane complex disassembly rates (K_diss) for syt1 were unchanged with the inclusion of 1 mol % PIP₂. Error bars, S.E. of four independent trials; **, p < 0.005; ns, p > 0.5; both by Welch's t test.