Although Mikhail Matz and colleagues might dispute that their isolation of a red fluorescent protein from a nonbioluminescent marine animal (Discosoma sp.) was serendipitous, their hypothesis was, at least, counterintuitive.1 The protein they found was only 26-30% identical to green fluorescent protein (GFP) at the amino acid level, yet it faithfully conserves GFP's b-can structure. Palo Alto, Calif.-based BD Biosciences-Clontech added this first generation fluorescent protein, DsRed1, to its Living Colors™ series—joining green, yellow, and cyan fluorescent variants to form a four-color palette.
Mutational tinkering by Clontech has doubled fluorescence intensity, decreased toxicity in vivo, halved expression time to 24 hours, and decreased aggregate formation while preserving the protein's overall structure.2 Like DsRed1, DsRed2 delivers a high signal-to-noise ratio and diminished autofluorescence, and its >50-nm red-shift from the nearest GFP variant both broadens the canvas and increases the accuracy of multi-fluorescence detection, whether through microscopy or FACS analysis.
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