Stimulation of the Ca2+-dependent polymerization of synexin by cis-unsaturated fatty acids

The influence of fatty acids on the polymerization of synexin was studied by monitoring light scattered from solutions of purified synexin. Cis-unsaturated fatty acids such as arachidonate or oleate stimulated synexin polymerization at sub-micromolar concentrations, while saturated fatty acids, a trans unsaturated fatty acid or a fatty acid methyl ester had little effect. The polymerization of synexin occurred at lower concentrations of Ca2+ in the presence of the fatty acids than in the absence of fatty acids. Therefore, Ca2+ and free fatty acids may act as co-regulators of synexin action in stimulated secretory cells.