Promoters of duplicated RP genes encode lower promoter activities. (A) Shown is a histogram of promoter activities of the promoters whose corresponding RP gene exists in two duplicate copies in the yeast genome (blue) and another histogram for the activities of promoters whose corresponding gene exists in one copy (orange). Also shown is the T-test P-value of the difference between the two histograms (top left). (B) The promoter activity variability of RP promoters is significantly reduced when summing pairs of duplicated RP promoters. For each of the 41 pairs of duplicate RP genes for which we have measurements for the two corresponding promoters, we added the promoter activities of the two promoters and computed the coefficient of variation (CV) of promoter activities of the promoter set that consists of these combined promoters and of RP promoters that have a single copy in the yeast genome (red arrow, CV = 0.27). For comparison, we computed the same coefficient of variation of activities when the pair of promoters whose activities are added were chosen at random. A histogram of 107 such permutations is shown (blue), and the P-value of the real RP promoter pairing is indicated (top left).
