Green fluorescence protein (GFP) is a 27KD protein derived from the jellyfish Aquorea victoria that emits a green light (emission peak at a wavelength of 509 nm) when excited by blue light (excitation peak at a wavelength of 395 nm). GFP is a highly versatile protein that has become an invaluable tool in cell biology research because of its intrinsic fluorescence without substrate requirement, ability to be visualized over time durations - both short- and long-term - in living cells, and short sequence making it easy to clone and use an unobtrusive tag.
