Locations of PAC and RRPE elements in 22 divergent gene pairs. A, sixteen divergent pairs with a single occurrence of the PAC-RRPE element; all the genes near the cis-elements are assigned to positive samples (red) except YIL090W-YIL091C. B, six gene pairs carry duplicate elements in their shared promoter region and are all considered positive samples for co-expression. Rectangles represent ORFs, lines between the ORFS are intergenic regions between the pair, and triangles indicate the binding sites for PAC and RRPE, respectively. Ruler at the bottom measures chromosomal distance.