Aequorin

Part of speech: noun

Definitions

1. A luminous protein obtained from jellyfish that responds to calcium ions by emitting light
2. A bioluminescent compound sourced from jellyfish, known for its light-emitting properties when interacting with calcium ions
3. A protein derived from jellyfish that fluoresces in response to calcium binding, commonly utilized in scientific and medical applications for its light-emitting capabilities

Etymology: Aequorin is named after the jellyfish genus it was first isolated from, "Aequorea", a name that itself comes from Greek roots meaning roughly "sea" and "to be". The suffix "-in" is the standard chemists' ending for a protein or other substance, so the name is a plain technical coinage: the genus name with a chemical ending attached. Nothing about it is a figure of speech or a myth; it simply tags the molecule by its source organism. The surprise lies in what the protein does. Its light is produced when calcium ions bind to it, which is why researchers have used it as a tool for tracking calcium signalling inside living cells. The name therefore records where the molecule was found, while its real importance lies in the chemistry of the glow.