Method of discovering chemicals capable of functioning as gene expression modulators

A method of determining whether a chemical not previously known to be a modulator of protein biosynthesis specifically transcriptionally modulates the expression of a gene-of-interest which comprises:

• (a) contacting a sample which contains a predefined number of identical eucaryotic cells with a predetermined concentration of the chemical to be tested, each comprising a single DNA construct consisting essentially of in 5' to 3' order
• (i) a modulatable transcriptional regulatory sequence of the gene-of-interest,
• (ii) a promoter of the gene-of-interest, and
• (iii) a reporter gene which expresses a polypeptide that produces a detectable signal, coupled to, and under the control of, the promoter, under conditions wherein the chemical if capable of acting as a transcriptional modulator of the gene-of-interest, causes a detectable signal to be produced by the polypeptide expressed by the reporter gene;
• (b) quantitatively determining the amount of the signal produced in (a);
• (c) comparing the amount of signal determined in (b) with the amount of signal produced and detected in the absence of any chemical being tested and with the amount of signal produced and detected upon contacting the sample in (a) with other chemicals, thereby identifying the test chemical as a chemical which causes a change in the amount of detectable signal produced by the polypeptide expressed by the reporter gene, and thereby determining whether the test chemical specifically transcriptionally modulates expression of the gene-of-interest.