title: Retrospective on the development of aequorin and aequorin-based imaging to visualize changes in intracellular free [Ca(2+) ].
abstract: In this review, we take a retrospective look at the discovery and utilization of the Ca(2+) -sensitive bioluminescent protein complex, aequorin. We do consider the contribution it has made to our understanding of the natural phenomenon of bioluminescence, but it is in the application of extracted and purified aequorin as a reporter of Ca(2+) dynamics in living cells, which is arguably its major contribution to biological and biomedical science. Following its extraction, purification, and subsequent availability in the mid-1960s, aequorin became the intracellular reporter of choice until it was replaced in the late 1970s by easier-to-use fluorescence-based reporters. From the mid-1980s onwards, however, aequorin-based Ca(2+) imaging underwent a renaissance following the cloning of the aequorin gene and the emergence of routine techniques to target and express it exogenously in plant and animal systems. The development of aequorin as a tool continues as spectral varieties are being developed that allow simultaneous imaging of Ca(2+) dynamics in different cellular organelles and microdomains. We predict that further developments in the use of aequorin, as well as other bioluminescent proteins, will continue, especially in the areas of regenerative medicine and whole organism imaging.
authors.affiliation: Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Kowloon, Hong Kong.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Webb
authors.affiliation: Science Wares, Inc., Falmouth, Massachusetts.
authors.forename: Eric
authors.initials: E
authors.lastname: Karplus
authors.affiliation: Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Kowloon, Hong Kong.|Marine Biological Laboratory, Woods Hole, Massachusetts.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Miller
mesh_terms: D000331:Aequorin / Q000737:chemistry*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D057054:Molecular Imaging / Q000266:history / Q000379:methods*
chemical_list: D000331:Aequorin; D002118:Calcium