Figure 1.1.
Three main classes of DNA-binding transcription factors. Diagrammatic representation of the three known classes of DNA-binding transcription regulators in bacteria, one-component (A), two-component (B), and group IV sigma factor (C). Transcription factors are depicted to bind DNA in the presence of an activating signal, but in some cases, the regulation is reversed and the transcription factors bind DNA only in the absence of the specific signal.