2008 Nobel Prize: Shedding light on Cells
Blog post by: Adrian English
Osamu Shimomura, Martin Chalfie and Roger Y. Tsien shared a Nobel Prize in 2008 for their work developing fluorescent proteins that can be used to illuminate cellular and protein processes.
The Auquorea victoria jellyfish produces a protein called ‘aequorin’ that has bioluminescent properties causing an emission of blue light when the protein interacts with calcium. This bioluminescent property causes the jellyfish to glow at its edges when observed in its habitat. The jellyfish also produces another, smaller, protein called ‘green fluorescent protein’ (GFP) which is fluorescent rather than luminescent. Rather than emitting light as a product of molecular change, a florescent protein absorbs the energy of ultraviolet light and re-emits the same energy within the visible light spectrum as green light.
The GFP has enabled biologists to improve their observational abilities due to the fact that additional chemicals do not need to be introduced into the subject to cause light emission. Using GFP requires gene splicing techniques. When a specific protein producing sequence of DNA has been targeted, the gene that produces GFP is spliced next to the target protein. When the target protein is expressed, so is the GFP causing fluorescence of the target protein when exposed to UV light. The target protein can be observed in real time allowing observation of structure and function. For example the relative position and intensity of the fluorescent light indicates where the protein has travelled and in what concentration.
This discovery and introduction of a new scientific tool has allowed researchers to test long standing hypothesis regarding protein transportation in the cell. For example the Golgi complex was originally thought to transport protein structures in a liner ‘conveyor belt’ like way through the membrane structure. Application of GFP techniques has shown that newly made proteins instead interact with other proteins and appear to ‘bounce’ within the compartments of the Golgi complex with a movement that more closely resembles the diffusion of a gas than a conveyor belt.
The GFP technique effectively superseded the practice of developing specific protein antibody markers and has the superior advantage of not requiring the subject to be ‘fixed’ (killed).
The original article can be found at:
http://www.nytimes.com/2008/10/14/science/14gree.html?_r=1
