General applications of GFP

"The crucial difference between GFP and [earlier, widely used dyes] is that it works [better] in live cells or animals." Roger Tsien, a GFP pioneer.

The fact that GFP's fluorescence requires no other cofactor: the fluorophore forms from the cyclization of the peptide backbone, makes GFP extremely useful as a biological marker. This feature makes the molecule a virtually unobtrusive indicator of protein position in the cells. And researchers have found that use of GFP as a tag does not alter the normal function or localization of the fusion partner.
Today, GFP has found its broad use in almost all organisms and all major cellular compartments. In cellular biology, GFP has been used as reporter gene, cell marker, fusion tag. GFP has also been used as an active indicator for protease action, transcription factor dimerization, calcium sensitivity etc. And in recent years, biochemical engineers have also found GFP's great ability to quantitatively monitor gene expression in different organisms.

The great attributes of GFP: It's these amazing qualities that make GFP so useful.
Green mouse? GFP could be cloned and expressed in almost all organisms. Here is a mouse with GFP gene.
GFP-tagged plakoglobin The fluorescent feature of GFP combined with the use of confocal microscopy helps researchers to determine protein localization. Her is an example where GFP helped to determine nuclear localization of polypeptides.