Redundant Mechanisms of Calcium-Induced Calcium Release Underlying Calcium Waves During Fertilization of Sea Urchin Eggs

Propagating Ca$^{2+}$ waves are a characteristic feature of Ca$^{2+}$-linked signal transduction pathways. Intracellular Ca$^{2+}$ waves are formed by regenerative stimulation of Ca$^{2+}$ release from intracellular stores by Ca$^{2+}$ itself. Mechanisms that rely on either inositol trisphosphate or ryanodine receptor channels have been proposed to account for Ca$^{2+}$ waves in various cell types. Both channel types contributed to the Ca$^{2+}$ wave during fertilization of sea urchin eggs. Alternative mechanisms of Ca$^{2+}$ release imply redundancy but may also allow for modulation and diversity in the generation of Ca$^{2+}$ waves.