Advancements in Genetic Engineering
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Negative Regulation

In negative regulation, a repressor protein binds to an operator to prevent a gene from being expressed. In positive regulation, a transcription factor is required to bind at the promoter in order to enable RNA polymerase to initiate transcription. A regulator gene, regulator, or regulatory gene is a gene involved in controlling the expression of one or more other genes. Regulatory sequences, which encode regulatory genes, are often at the five prime ends to the start site of transcription of the gene they regulate. In addition, these sequences can also be found at the three prime ends of the transcription start site. In both cases, whether the regulatory sequence occurs before or after the gene it regulates, the sequence is often many kilobases away from the transcription start site. A regulator gene may encode a protein, or it may work at the level of RNA, as in the case of genes encoding microRNAs. An example of a regulator gene is a gene that codes for a repressor protein that inhibits the activity of an operator (a gene that binds repressor proteins thus inhibiting the translation of RNA to the protein via RNA polymerase).