dna locations with the consensus sequence CANNTG. ENHANCER elements may contain multiple copies of this element. E-boxes play a regulatory role in the control of transcription. They bind with basic helix-loop-helix (bHLH) type transcription factors. Binding specificity is determined by the specific bHLH heterodimer or homodimer combination and by the specific nucleotides at the 3rd and 4th position of the E-box sequence.