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. 2009 Jun 19;106(27):11107–11112. doi: 10.1073/pnas.0904837106

Fig. 4.

Fig. 4.

Michaelis–Menten curves (blue) for CLK/BMAL1 activation of Per2 with Cry2 knockout (A); PER1/CRY1 inhibition of Per2 with Cry2 knockout (B); PER2/CRY1 inhibition of Per2 with Cry2 knockout (C); CLK/BMAL1 activation of Per2 with Cry1 knockout (D); PER1/CRY2 inhibition of Per2 with Cry1 knockout (E); and PER2/CRY2 inhibition of Per2 with Cry1 knockout (F). The portions of the curves highlighted in red are the regions traversed, given the model-predicted concentrations of CLK/BMAL1 or the relevant PER/CRY. Curves in A–C, which pertain to Cry2 knockout, when multiplied together can yield a variety of gene activity levels, while curves in D–F, which pertain to Cry1 knockout, when multiplied together lead to near-inactivation of transcription.