Practice question

Green fluorescent protein from jellyfish Aequorea victoria contains internal tripeptide Ser65-Tyr66-Gly67 that undergoes autocatalytic cyclization and oxidation to form p-hydroxybenzylidene-imidazolinone chromophore requiring no exogenous cofactor. When fused to protein of interest, chimera exhibits intrinsic fluorescence excitable at 395 and 475 nm, emitting at 509 nm, allowing direct visualization on gel documentation systems or after blotting using anti-GFP antibodies. Utility does not derive from heat emission, blocking ability, or binding inhibition. Self-sufficient fluorophore formation makes GFP valuable reporter for localization, expression, and fusion protein detection.