In A. victoria, GFP fluorescence occurs when aequorin interacts with Ca2+ ions, inducing a blue glow. Some of this luminescent energy is transferred to the GFP, shifting the overall color towards green.

The Green Fluorescent Protein (GFP) is a versatile biological marker for monitoring physiological processes, visualizing protein localization, and detecting transgenic expression in vivo. GFP can be excited by the 488 nm Fluorescence Flashlight GRPfinder and is optimally detected at 510 nm.

Why does GFP glow under UV light?

Solutions of purified GFP look yellow under typical room lights, but when taken outdoors in sunlight, they glow with a bright green color. The protein absorbs ultraviolet light from the sunlight, and then emits it as lower-energy green light.

Figure below: GFP expression under Fluorescence Flashlight