Abstract
Green fluorescent protein (GFP) is a protein isolated from the Pacific jellyfish, Aequorea victoria. Its role is to transduce, by energy transfer, the blue chemiluminescence of another protein; aequorin, into green fluorescent light. Green fluorescent protein is comprised of 238 amino acids. It has a chromophore which originates from an internal Ser-Tyr-Gly (SerineTyrosine-Glycine) sequence. The chromophore absorbs ultra violet light maximally at 470 nm and emits green fluorescence at 509 nm. The green fluorescent protein has mutated versions which are brighter, absorb light of different wavelengths, and glow in different colours such as cyan, blue and yellow. GFP can be expressed as a functional transgene and this has opened exciting new avenues of investigation in cell, developmental and molecular biology. GFP has been expressed in bacteria, yeast, slime mold, plants, drosophila, zebra fish, and in mammalian cells. GFP can function as a protein tag, as it tolerates N- and C-terminal fusion to a broad variety of proteins many of which have been shown to retain native function. The enormous flexibility as a non-invasive marker in living cells allows for numerous other applications such as a cell lineage tracer, biosensor, reporter of gene expression and as a potential measure of protein-protein interactions. Green fluorescent protein has revolutionized cell labeling and molecular tagging.

Key words: Green fluorescent protein, Aequorea victoria, Aequorin, Fluorescence microscopy, Molecular tagging, Cell biology, Biosensors