regulatory gene In the operon theory of gene regulation, a gene that is involved in switching on or off the transcription of structural genes. When transcribed, the regulatory gene produces a repressor protein, which switches off an operator gene and hence the operon that this controls. The regulatory gene is not part of the operon, and may even be on a different chromosome.

regulator gene In the operon theory of gene regulation, a gene that is involved in switching on or off the transcription of structural genes. When transcribed, the regulator gene produces a repressor protein, which switches off an operator gene and hence the operon that this controls. The regulator gene is not part of the operon, and may even be on a different chromosome. See also REPRESSOR.

regulatory genes Genes that control development by regulating the expression of structural genes responsible for the formation of body components. They encode transcription factors, which interact with regulatory sites of other genes causing activation or repression of developmental pathways. Much of development in quite different organisms, such as mammals and insects, is controlled by genes that are structurally very similar, thought to descended from genes in ancient common ancestors. Prime examples are the homeotic genes, such as the Hox genes of mammals.

regulator gene See operon.