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 biochemical interactions with the genome and the environment. One organism will have radically different protein expression in different parts of its body, in different stages of its life cycle and in different environmental conditions.
The entirety of proteins in existence in an organism throughout its life cycle, or on a smaller scale the entirety of proteins found in a particular cell type under a particular type of stimulation, are referred to as the proteome of the organism or cell type respectively.
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 that code for proteins in the human genome than there are proteins in the human proteome (~22,000 genes vs ~200,000 proteins). The large increase in protein diversity is thought to be due to post-translational modification of proteins.
To catalogue all human proteins and ascertain their functions and interactions presents a daunting challenge for scientists. An international collaboration to achieve these goals is being co-ordinated by the Human Proteome Organisation (HUPO (http://www.hupo.org)).
Key technologies used in proteomics
- One and two-dimensional electrophoresis are used to identify the relative mass of a protein and its isoelectic point.
- X-ray crystallography and nuclear magnetic resonance are used to characterize the three-dimensional structure of peptides and proteins.
- Tandem mass spectrometry combined with reverse phase chromatography or 2D gel electrophoresis is used to identify and quantify all the levels of proteins found in cells.
- Affinity chromatography, yeast two hybrid techniques, fluorescence resonance energy transfer (FRET), and Surface Plasmon Resonance (SPR) are used to identify protein-protein and protein-DNA binding reactions.
External links and sources
- In 2004 the estimated number of genes in genome dropped from 33,000 to 20,000-25,000 (http://web.mit.edu/newsoffice/2004/humangenome.html)
|Topics within genomics|
|Genome project | Glycomics | Human Genome Project | Proteomics | Structural genomics|
|Bioinformatics | Systems biology|