mCherry protein is derived from a natural product, DsRed, originally isolated as a red fluorescent protein from the coral of the genus Discosoma (1). As with other natural fluorescent proteins of
Cnidarians (jelly fish, sea anemones, and corals), the natural form of the protein forms stable tetramers in vivo. DsRed was engineered to improve its spectral properties and also prevent ultimerization in the Tsien lab, where much work on fluorescent proteins was performed (2). Roger Tsien, along with Martin Chalfie, and Osamyu Shinomura shared the 2008 Nobel prize in chemistry for
the discovery and exploitation of Cnidarian fluorescent proteins. Several further cycles of mutation, directed modification and evolutionary selection produced mCherry, which is monomeric and has an
excitation maximum at 587nm and emission maximum at 610nm (3). The protein is widely used as a fluorescent tracer in transfection, transgenic, photobleaching and FRET type experiments. The prototype for these fluorescent proteins is Green Fluorescent Protein (GFP), which is a ~27kDa protein isolated originally from the jellyfish Aequoria victoria (4). The mCherry protein is similar in size and general structural properties to GFP (5,6), but, obviously, produces a red rather than a green fluorochrome. As with GFP, mCherry becomes fluorescent due to intrinsic properties requiring only molecular oxygen and so can be readily expressed in a variety of systems.