Apoaequorin

Apoaequorin is the apoprotein (protein component) of aequorin, a calcium-binding photoprotein originally isolated from the jellyfish *Aequorea victoria*[1][2][5]. Apoaequorin contains three EF-hand calcium-binding motifs and serves as the protein scaffold that binds the small molecule coelenterazine; together they form active aequorin, which emits light in response to binding calcium ions[1][6]. Apoaequorin itself is non-luminescent and is used in research as a precursor to photoproteins for tracking intracellular calcium. In dietary supplements, it is marketed as an ingredient for cognitive health (e.g., in Prevagen), but strong evidence shows that apoaequorin is quickly digested in the gastrointestinal tract and does not reach the brain, making systemic or CNS effects unlikely[5][7][8]. Apoaequorin is not a receptor, enzyme, or traditional drug target and does not have recognized roles as a therapeutic target in disease management[5]. The FDA has challenged health claims made for oral apoaequorin, and there is no established role for it in clinical diagnostics or therapy[5][8].