Effect of competition by Sum1p on predicted binding by Ndt80p. Sequence logos  for (a) Ndt80p and (b) Sum1p binding specificity. (c) Values for the area under the receiver operating characteristic curve (ROC AUC) quantify how well predicted Ndt80 binding distinguishes regulated genes from non-regulated genes. The regulated gene sets are the genes controlled by Ndt80 only (black), Sum1 only (white), or both (gray). For all comparisons, the set of non-regulated genes consists of genes not regulated by Ndt80 or by Sum1. Sum1p concentration is expressed as a ratio to the optimal predicted Kd value for Sum1p binding; Ndt80p concentration is set equal to the optimal predicted Kd value for Ndt80p binding. The regulatory region was defined by the uniform weight function over the sequence between 600 base pairs 5' to the open reading frame and the start of translation.