GFP(Green fluorescent protein) is an energy-transfer
acceptor. Its role is to transduce the blue chemiluminescence
of the protein aequorin into green fluorescent light by energy transfer. Fluoresces in vivo upon receiving energy from the Ca(2+)-activated
photoprotein aequorin. It contains a chromophore consisting of modified amino acid residues. The chromophore is formed by autocatalytic backbone condensation between Xaa-N and Gly-(N+2), and oxidation of Tyr-(N+1) to didehydrotyrosine. Maturation
of the chromophore requires nothing other than molecular oxygen.
Fluorescent proteins have become a useful and ubiquitous tool for making chimeric proteins, where they function as a fluorescent protein tag. Typically they tolerate N- and C-terminal fusion to a broad variety of proteins. They have been expressed in most known cell types and are used as a noninvasive
fluorescent marker in living cells and organisms.
They enable a wide range of applications where they have functioned as a cell lineage tracer, reporter of gene expression, or as a measure of protein-protein interactions.