Preparation and use of sea urchin egg homogenates for studying NAADP-mediated Ca²⁺ release.

NAADP and other Ca-mobilizing messengers are membrane impermeant and thus must be added directly to cell-free or broken-cell preparations to effect Ca release. The sea urchin egg homogenate, where the biological activity of NAADP was first reported, remains the gold standard cell-free system for studying NAADP-mediated Ca release. Here we describe how to prepare sea urchin egg homogenate and use it to measure NAADP-mediated Ca release.