Cloning and expression of the cDNA coding for aequorin, a bioluminescent calcium-binding protein

Aequorin is a bioluminescent protein which consists of a polypeptide chain (apoaequorin), coelenterate luciferin, and bound oxygen. Aequorin produces blue light upon binding Ca 2+. We have isolated six recombinant pBR322 plasmids which contain apoaequorin cDNA sequences. A mixed synthetic oligonucleotide probe was used to identify these cDNAs. An extract of an E . coli strain possessing the largest cDNA contained apoaequorin. This apoaequorin can be converted to aequorin in the presence of coelenterate luciferin, 2-mercaptoethanol, and O 2. This cDNA is therefore apparently full-length.