Fig. 2.

Ca²⁺-dependent phospholipid binding properties of SytWT, SytC2A^3W, SytC2B^3W, and SytC2A^3WC2B^3W. Wild-type or mutant forms of GST-synaptotagmin 1 C2AB domains were incubated with liposomes (41% phosphatidylcholine, 32% phosphatidylethanolamine, 10% phosphatidylserine, 5% phosphatidylinositol, 10% cholesterol) containing no PIP and PIP₂ (Upper), or 0.25% PIP + 0.05% PIP₂ (Lower) in the presence of free Ca²⁺ at the concentrations shown, clamped by Ca²⁺/Mg²⁺/EGTA buffers. Liposomes were centrifuged and washed, and bound proteins were analyzed by SDS/PAGE and Coomassie blue staining. Data shown are representative of experiments performed multiple times.