Summary of experimental evidence on the main calcium channels proposed in the pathway activated by SAPs.

aIt is worthwhile to mention that out of the pharmacological blockers listed, none of them are 100% specific to the associated channels. bAntibody raised against a polypeptide of the α subunit in rat, which also recognises the homologous version in mouse and human sperm. cAntibody raised against pore-forming subunit polypeptides of A. punctulata [12] and S. purpuratus [18]. d It is of note that direct electrophysiological recordings for this ion channel have not been achieved in mature sea urchin spermatozoa compared with the homologous complex in mouse, human and macaque spermatozoa [19].