A cluster of regulatory base sequence in a DNA molecule that can initiate or increase the transcription of a gene by binding a specific protein called activators (see transcription factor). An enhancer may be some distance, perhaps thousands of nucleotides, from the gene it controls on the same chromosome, and typically interacts with other enhancer and repressor sites to regulate the binding of RNA polymerase to the DNA molecule and hence expression of the gene. One proposed mechanism involves bending of the DNA molecule so that the enhancer site with its bound activators is brought close to the promoter of the gene, so forming an active initiation complex with other transcription factors and enabling transcription to proceed.