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Figure 1. A simplistic view of regulatory mechanisms of gene transcription. The RNA-transcribing enzyme, RNA polymerase II (red), requires general transcription factors (TFII) D, A, B, F, E, and H (blue), which themselves consist of multiple subunits, to recognize the transcription start site via the TATA box or related sequences in the core promoter. The sum of these factors, known as the pre-initiation complex (PIC), is required for basal transcription. Transcription factors (green) bind to specific DNA sequences (red) via their DNA-binding domain (DBD) and modulate the rate of transcription via their transactivation domain(s) (TAD).
