The numbers come to light

The trouble with systems biology is that no one wants to make all those measurements. Rate constants and binding assays are just not that exciting. Now, Michal Ronen, Uri Alon (Weizmann Institute of Science, Rehovot, Israel), and colleagues have come up with a method for rapidly determining the expression profiles of thousands of genes, and extrapolating from those profiles to derive protein concentrations and predict responses to other conditions.

The test case for this system is simple enough. The researchers linked GFP to eight operons in the Escherichia coli SOS DNA repair system. This system is controlled by a single repressor LexA. For each operon, Alon determined β, the unrepressed production rate, and k, the effective affinity of the LexA repressor based on half-maximal repression. This work...