Figure 4.

Ca²⁺ dependence of binding of synprint peptides to synaptotagmin. (A–C) Binding of the synprint peptides from α_1B, α_1A(BI), and α_1A(rbA) to immobilized GST-synaptotagmin was measured as described in Experimental Procedures and the legend to Fig. 1 at the indicated concentrations of Ca²⁺. Concentrations of GST proteins were visualized by staining with Ponceau S. (D) Results of three experiments like the one in B were quantitated by densitometry, averaged, and plotted as mean ± SEM vs. Ca²⁺ concentration.