How does studying the proteome compare to studying the genome? What are some of the challenges in proteomics research?
The total number of proteins in human cells is estimated to be between 250 to 500 thousand, and only a small percentage have been sequenced or identified. The complete proteome has not been characterized for any organism. In contrast, the genome or the entire set of genes for several organisms has been sequenced, including humans. The human genome is estimated to contain about 35,000 protein-encoding genes (http://www.genome.gov/10002192). Besides the difference in quantity, another important difference between the genome and proteome is that the genome is static and relatively unchanged from day to day. Cellular proteins, on the other hand, are continually moving and undergoing changes such as binding to a cell membrane, partnering with other proteins, gaining or losing a chemical group such as a sugar, fat, or phosphate, or breaking into two or more pieces. Proteins play a central role in the complex communication network within and between cells and are constantly responding to the
