 Aequorin belongs to the EF-hand family of CaBPs, with EF-hand loops that are closely related to CaBPs in mammals.In addition, aequorin has been used for years as an indicator of Ca2+ and has been shown to be safe and well tolerated by cells.Aequorin is made up of two components – the calcium binding component apoaequorin (AQ) and the chemiluminescent molecule coelenterazine.