We’ve all seen the photos of fluorescent (=emission of absorbed light) mice or glowing plants. A lot of these pictures are not understood and most people will only see them as a strange experiment only done with fun in mind. On the contrary, the researches are very important and the use of this protein is enormous.
Why is this protein so useful?
Due to genetic manipulation by researchers we are able, together with the help of a few enzymes and techniques, to ‘paste in’ the DNA for this protein and make it stick to another protein. Due to the properties of the fluorescent protein we can make it visible by light alone. So if I for example would want to watch the production of insulin in cells I would only have to ‘paste’ the DNA of GFP onto the DNA of insulin and it would create an insulin protein with a GFP protein hanging off the end of it. Made visible with a UV light, the amount of glow is equal to the amount of insulin made. It’s also used for example to track movement inside cells. You can also colour entire cell parts to see how they move and where they move to. It’s even possible to figure out the spread of cancer cells by following the light and following the cells movement!
Where does this protein come from?
GFP is an abbreviation of ‘green fluorescent protein’ and the gene for this protein has been extracted from the Aequora victoria also called the crystal jellyfish. This protein has first been extracted in 1962 by Shimomura et al. Shimomura, Chalfie and Tsien shared a Nobel Prize for Chemistry in 2008.
But why does this protein glow?
In short, this protein is able to ‘absorb’ the energy it gets from dark blue, purple and UV light and it subsequently emits green light to get rid of the energy it has absorbed. There are lots and lots of variations of this fluorescent protein which all have other colours so it makes it possible for researchers to study multiple processes at the same time. Examples of these colours are RFP, BFP, CFP, YFP. Red, blue, cyan and yellow respectively. An example is this picture, a photo of mice’s neurons coloured with lots of different fluorescent proteins.
In conclusion, this protein has enabled scientists around the world to watch biochemical processes in real-time in living cells, opening a whole world for scientists to do research on cell processes and cell interactions.
References for pictures;
“Brainbow” – Livet, J. et al. (2007). Transgenic strategies for combinatorial expression of fluorescent proteins in the nervous system. Nature 450, 56-62.
Extra links for people interested in more of the like;
National Geographic segment on fluorescent proteins in transgenic animals; http://news.nationalgeographic.com/news/2009/05/photogalleries/glowing-animal-pictures/
About chromophores, parts of molecules which are responsible for the glow;
Fan Yang et al. (1996) The Molecular Structure of Green Fluorescent Protein Nature Biotechnology 14, 1246 – 1251