Hill function inhibitory response.

<p>Hill function inhibition of gene expression is approximated by the transistor current's dependence on input voltage <i>V</i><sub>i-1</sub> for the circuit in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0023286#pone-0023286-g001" target="_blank">Fig. 1</a>. Hill function (red dashed line), predicted current (green solid line), and measured current (blue dots). Maximum transistor current of 3 mA corresponds to maximum transcription rate α = 60. The Hill coefficient is <i>n</i> = 3.75.</p>