FUNCTION: 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. BIOPHYSICOCHEMICAL PROPERTIES: Excitation max (nm): 488; Emission max (nm): 509; Extinction coefficient (Cm-1M-1): 61000. SUBUNIT: Monomer. TISSUE SPECIFICITY: Photocytes. PTM: 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. BIOTECHNOLOGY: 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. SIMILARITY: Belongs to the GFP family.
