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Proteomics

Proteomics is the large-scale study of proteins, particularly their structures and functions. This term was coined to make an analogy with genomics, and is often viewed as the "next step", but proteomics is much more complicated than genomics. Most importantly, while the genome is a rather constant entity, the proteome is constantly changing through its interactions with the genome. One organism will have radically different protein expression in different parts of its body and in different stages of its life cycle.

With completion of a rough draft of the human genome, many researchers are now looking at how genes and proteins interact to form other proteins. A surprising finding of the Human Genome Project is that there are far fewer genes in the human genome than there are proteins (~33,000 genes:~200,000 proteins). This finding shatters the early "one gene = one protein" hypothesis and presents a daunting challenge for scientists: To catalogue all human proteins and ascertain their function and interactions. Some have dubbed this the "Human Proteome Project", but no official title has yet been adopted.

Key technologies used in proteomics research include mass spectrometry[?], x-ray crystallography, NMR and gel electrophoresis.

There are two major approaches to proteomics - study of in-vivo samples vs. synthesizing recombinant proteins. In the second instance, genetic engineering techniques are used to clone the DNA template for the protein being synthesized and to splice these gene into host cells, typically bacteria, which are made to express the protein in large scale.

The protein then has to be extracted from the host cells and purified. Subsequently, the pure protein is submitted for crystallization (and then x-ray) or NMR for structural determination. NMR is not effective for large proteins.

Proteomics is a greater challenge than genomics because the 3-dimensional geometry of proteins is critical in their function. It is important and challenging to preserve this geometry through all the steps described above.