Four representative TF–TFBS pairs are shown in ribbon diagram. ( a ) AAACA–IRHNL pair in 3C06, ( b ) GATAA–NACGL pair in 3DFV, ( c ) GGTCA–GFFRR pair in 3DZY and ( d ) CTTCC–LRYYY pair in 2NNY are shown. The TF amino acids and TFBS nucleotides are highlighted in ball and stick format. The sequences of the TF–TFBS pairs are also labeled in the figures. The figures are generated using Protein Workshop ( 34 ).