Fig. 2
From: Genetic tool development and systemic regulation in biosynthetic technology
a GFP: green fluorescent protein. Toggle switches possess two repressors (R1 and R2) and two promoters (P1 and P2). R1 is transcribed by P2 and can inhibit P1. R2 is transcribed by P1 and can inhibit P2. In addition, R1 is inducted by Inducer1 and R2 is inducted by Inducer2. The transcriptional states can be flipped by adding inducers. b LacI inhibits the transcription of TetR, and then TetR inhibits the expression of CI. Finally, CI inhibits LacI expression, LacI inhibits the transcription of TetR, and TetR inhibits the expression of CI and GFP