Positive Autoregulation Delays the Expression Phase of Mammalian Clock Gene Per2
(A) Schematic representation of the circadian oscillatory network model used to compare the expression phases of Per1 and Per2 mRNAs, which was based on the Leloup and Goldbeter model . The Per2 gene transcription and translation are additionally introduced in the shaded region. A square, wave line, and circle indicate a gene, mRNA, and protein, respectively. Details are described in Text S1. (B, C) Variation in the phase difference between the Per1 and Per2 mRNA oscillations with varied (B) the proportion of the Per1 transcription rate coefficient to the Per2 transcription rate coefficient (vsP1/vsP2) and (C) the proportion of the Per1 degradation rate coefficient to the Per2 degradation rate coefficient (vmP1/vmP2). The rate coefficient of transcription and degradation of Per2 were fixed to 2.4 nM/h and 2.2 nM/h, respectively. The phase difference of Per1 from Per2 is indicated in circadian time (CT).