Oligomerization of transcription factors (TF) and miRNAs induce thresholds in protein expression.

<p>(A) Minimal model for protein synthesis including a miRNA. TF activate, with or without oligomerization of TF, the synthesis of a messenger RNA (RNA). This RNA can form an inhibitory complex, RNA_i, with a miRNA, which prevents it to encode the synthesis of the protein. We assume that the level of each component in the model can be controlled by synthesis and degradation. Steady-state levels of protein <i>vs</i> the level of TF are shown for different degrees of oligomerization of TF (n) in B, and for different rates of synthesis of miRNA (<i>V</i>_SMIRNA) in C. Horizontal red lines indicate an arbitrary threshold of protein needed to promote a cellular response. (D) Steady-state levels of protein <i>vs V</i>_SMIRNA for different rate constants of association between the RNA and the miRNA, <i>k</i>₁. Parameter values used in the simulations are as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083372#pone-0083372-t002" target="_blank">Table 2</a>.