title: The use of aequorin and its variants for Ca2+ measurements.
abstract: Ca(2+)-sensitive photoproteins are ideal agents for measuring the Ca(2+) concentration ([Ca(2+)]) in intracellular organelles because they can be modified to include specific targeting sequences. Aequorin was the first Ca(2+)-sensitive photoprotein probe used to measure the [Ca(2+)] inside specific intracellular organelles in intact cells. Aequorin is a 22-kDa protein produced by the jellyfish Aequorea victoria. On the binding of Ca(2+) to three high-affinity sites in aequorin, an irreversible reaction occurs in which the prosthetic group is released and a photon is emitted. Aequorin has become widely used for intracellular Ca(2+) measurements because it offers many advantages: For example, it can be targeted with precision, functions over a wide range of [Ca(2+)], and shows low buffering capacity. In this article we describe the main characteristics of the aequorin probe and review the reasons why it is widely used to measure intracellular [Ca(2+)].
authors.affiliation: Department of Biomedical Sciences, University of Padua and CNR Neuroscience Institute, 35131 Padua, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Granatiero
authors.forename: Maria
authors.initials: M
authors.lastname: Patron
authors.forename: Anna
authors.initials: A
authors.lastname: Tosatto
authors.forename: Giulia
authors.initials: G
authors.lastname: Merli
authors.forename: Rosario
authors.initials: R
authors.lastname: Rizzuto
mesh_terms: D000331:Aequorin / Q000302:isolation & purification; D000818:Animals; D002118:Calcium / Q000032:analysis*; D003600:Cytosol / Q000737:chemistry; D037402:Hydrozoa; D015388:Organelles / Q000737:chemistry; D017785:Photons; D011485:Protein Binding
chemical_list: D000331:Aequorin; D002118:Calcium