Co-regulation vs. Functional Similarity as Defined by Minimum Node Count A, B and C were created using the biological process, molecular function and cellular component ontologies, respectively. The dark black lines are fit using the actual yeast data (individual data points represented as blue ●). The thin red lines are fit using data where the mapping between genes and their promoters is permuted. For clarity, the individual data points representing permuted data are not shown. For each of the three ontologies, the fraction of gene pairs sharing a common transcription factor binder increases as functional similarity increases (i.e. as the minimum node count decreases).