the fusion of fluorescent tags to proteins in a host cell is a widely popular technique used in experimental cell and biology research in order to track protein interactions in real time. the first fluorescent tag, green fluorescent protein (gfp), was isolated from "aequorea victoria" and is still used frequently in modern research. more recent derivations include photoconvertible fluorescent proteins (pcfps), which were first isolated from "anthozoa". the most commonly used pcfp is the kaede fluorescent tag, but the development of kikume green-red (kikgr) in 2005 offers a brighter signal and more efficient photoconversion. the advantage of using pcfp fluorescent tags is the ability to track the interaction of overlapping biochemical pathways in real time. the tag will change color from green to red once the protein reaches a point of interest in the pathway, and the alternate colored protein can be monitored through the duration of pathway. this technique is especially useful when studying g-protein coupled receptor (gpcr) recycling pathways. the fates of recycled g-protein receptors may either be sent to the plasma membrane to be recycled, marked by a green fluorescent tag, or may be sent to a lysosome for degradation, marked by a red fluorescent tag.