Green Fluorescent protein

From a jellyfish the naturally green fluorescent protein (GFP) may be tagged on to other proteins and utilized to visualize the location and movement of proteins in living cells by fluorescent microscopy.

By the discovery of a naturally fluorescent protein which  found in the jellyfish  Aquorea  victoria ,Visualization of proteins in living cells has been revolutionized.  In this 238 amino  acid protein which is called  green  fluorescent  protein  (GFP),  certain  amino acid side-chains  have cyclized  to form a green-fluorescing chromophore spontaneously. By  Using recombinant  DNA techniques, the DNA encoding GFP may be tagged on to the DNA sequences encoding other proteins, and then in culture or into particular cells of a entire animal introduced  into living cells.  Cells  containing  the  introduced  gene  will  then  produce  the  protein tagged with GFP that will fluoresce  green under the fluorescent  microscope. In  real  time localization  and movement  of the GFP-tagged  protein can then be studied in  living  cells. Multiple  variations  of  GFP  have  been  engineered at different  wavelengths which  emit  light, for instance cyan  fluorescent  protein  (CFP) and yellow fluorescent  protein (YFP), in the same cell permitting several proteins to be visualized simultaneously.