The repressilator (ring oscillator) designed and built by Elowitz and Leibler, drawn using SBOL Visual. Comprises three repressor motifs, each taken from a different type of DNA sequence or organism: LacI from E. coli, tetR from the tetracycline-resistance transposon Tn10, and cI from λ phage. lacI, tetR, cI, and gfp are protein-coding genes; LacI, TetR, CI, and GFP are the protein products. The three repressor motifs are organised in a ring on a repressilator plasmid, and gfp is located on a separate reporter plasmid, but they have been drawn here separately for clarity.