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Figure 2 | BMC Evolutionary Biology

Figure 2

From: Upstream plasticity and downstream robustness in evolution of molecular networks

Figure 2

Divergence of the upstream transcriptional regulation of duplicated genes in yeast. A) The distribution of the regulatory overlap Ω reg of paralo-gous proteins. The y-axis – Ω reg – is the number of transcription factors that cis-regulate both genes encoding a given pair of paralogous proteins. The x-axis is the percent identity (PID) of amino acid sequences of these two proteins. The colorbar shows the likelihood of finding a given Ω reg in a given 10% PID bin (note the logarithmic scale). The data describing the yeast regulatory network were taken from the whole genome chip-on-chip binding assay of 106 transcription factors [2], while the list of pairs of paralogous proteins was obtained by the whole genome blastp search (see Methods for more details.). B) The PID dependence of the average regulatory overlap Ω reg normalized by the total number of regulators of either one or the other paralog. Relative error bars are estimated by the inverse square root of the total number of shared regulators in a given PID bin. The solid line is the best fit to the exponential form: Ω reg ~ exp(γ PID) with γ = 0.03 (3% change in Ω reg for every 1% change in PID.) The dashed horizontal line at 0.015 is a null-model expectation of the normalized overlap of two randomly selected proteins (not necessarily paralogs).

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