A combined force of chemical genetics and protein microarrays

To date, the genomic sequences of over 200 organisms have been determined (http://www.ncib.nlm.nih.gov). The science of genomics has revolutionized both basic research and drug discovery. DNA microarray technology, in particular, has become a routine tool to profile the expression of thousands of genes and even the entire gene repertoire of an organism. Similar approaches have been applied to identify genes that are differentially expressed in response to drug treatments, which in turn facilitates genomics-based drug discovery and disease classification. However, a major drawback to such approaches is that differences in gene expression profiles usually do not provide direct links to the causative elements (drugs) and, in some cases, may not be related to them at all. Further, cellular functions are mostly executed by genes that encode proteins, whose activities are often controlled, modified and regulated by other proteins. Thus, determining the biochemical activities of each protein, how they might assemble together to carry out the biochemical reactions and cellular events, and also how they may function in a sequential pathway or collaborative network are crucial to elucidating the molecular basis of complex processes.