The sperm-activating peptides (SAPs) are isolated in egg-conditioned media (egg jelly) of sea urchins. SAPs have several effects on sea urchin spermatozoa: stimulate sperm respiration and motility through intracellular alkalinization, transient elevation of cAMP, cGMP and Ca++levels in sperm cells.
Jiyao W et al.(2023). "The conserved domain database in 2023.",