What is proteomics?

Proteomics is determining the entire protein content of a particular sample, be it a microorganism, cultured cell line, organelle, tissue or whole organism. While the genome of an organism is rather constant, the proteome can differ from cell to cell and change constantly as the cell interacts with its own genome and the environment. In addition, proteins undergo post-translational modifications and their interactions with other proteins effect cells in ways not predicted by the genome.

The Human Genome Project has found that there are far fewer protein-coding genes in the human genome than proteins in the human proteome (20,000 to 25,000 genes vs. > 500,000 proteins). The protein diversity is thought to be due to alternative splicing and post-translational modification of proteins. The discrepancy implies that protein diversity cannot be fully explained by genomics and proteomics is then necessary to determine what proteins are expressed and how they are regulated in different states of the cell.

The main tools of proteomic projects are two-dimensional gel electrophoresis and multi-dimensional chromatography techniques coupled to mass spectrometry.