<chemical> A photoprotein isolated from the bioluminescent jellyfish aequorea. It emits visible light by an intramolecular reaction when a trace amount of calcium ion is added. The light-emitting moiety in the bioluminescence reaction is believed to be 2-amino-3-benzyl-5-(p-hydroxyphenyl)pyrazine (af-350).
Chemical name: Aequorins