(a) Functional MSEs are located in preferred positional windows. Genes in the test set were analyzed for the location of the core MSE sequence, CRCAAA, in four yeast species. The inset shows the distribution of the locations of the MSE in the whole genome promoters. All the distributions were normalized by the number of available promoter sequences at the given location. (b) The distributions of binding scores for the MSE sites in the test gene set (red dashed curve) and in the whole genome (solid black curve).