Fluorescent Protein–photoprotein Fusions and Their Applications in Calcium Imaging1. (25th January 2017)

• Record Type: Journal Article
• Authors: Bakayan, Adil; Domingo, Beatriz; Vaquero, Cecilia F.; Peyriéras, Nadine; Llopis, Juan
• Is Part Of: Photochemistry and photobiology. Volume 93:Number 2(2017)
• Page Start: 448
• Page End: 465
• Publication Date: 2017-01-25
• Subjects: Photochemistry -- Periodicals; Light -- Physiological effect -- Periodicals; 541.35
• DOI: 10.1111/php.12682
• Languages: English
• ISSNs: 0031-8655

Abstract

Abstract: Calcium‐activated photoproteins, such as aequorin, have been used as luminescent Ca 2+ indicators since 1967. After the cloning of aequorin in 1985, microinjection was substituted by its heterologous expression, which opened the way for a widespread use. Molecular fusion of green fluorescent protein (GFP) to aequorin recapitulated the nonradiative energy transfer process that occurs in the jellyfish Aequorea victoria, from which these two proteins were obtained, resulting in an increase of light emission and a shift to longer wavelength. The abundance and location of the chimera are seen by fluorescence, whereas its luminescence reports Ca 2+ levels. GFP‐aequorin is broadly used in an increasing number of studies, from organelles and cells to intact organisms. By fusing other fluorescent proteins to aequorin, the available luminescence color palette has been expanded for multiplexing assays and for in vivo measurements. In this report, we will attempt to review the various photoproteins available, their reported fusions with fluorescent proteins and their biological applications to image Ca 2+ dynamics in organelles, cells, tissue explants and in live organisms. Abstract : The Ca 2+ ‐activated photoprotein aequorin has been widely used to measure Ca 2+ dynamics in cells and living organisms. Chimeric fusion proteins between GFP or related fluorescent proteins and aequorin have been constructed to provide various hues for multicolor imaging or for multiplexing assays. These genetically encoded Ca 2+ indicators, whose expression levels can be conveniently followed by fluorescence, show increased stability within live cells and enhanced total luminescence capacity. We review the available photoproteins, the rationale and strategies used for shifting their emission, and examples of biological applications targeted to organelles, microdomains, cell types or in vivo in transgenic organisms.