Regulator gene

A regulator gene, regulator, or regulatory gene is a gene involved in controlling the expression of one or more other genes. 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 gene (a gene which binds repressor proteins thus inhibiting the translation of RNA to protein via RNA polymerase).[1]

In prokaryotes, regulator genes often code for repressor proteins. Repressor proteins bind to operators or promoters, preventing RNA polymerase from transcribing RNA. They are usually constantly expressed so the cell always has a supply of repressor molecules on hand.[2] Inducers cause repressor proteins to change shape or otherwise become unable to bind DNA, allowing RNA polymerase to continue transcription. Regulator genes can be located within an operon, adjacent to it, or far away from it.[3]

Other regulatory genes code for activator proteins. An activator binds to a site on the DNA molecule and causes an increase in transcription of a nearby gene. In prokaryotes, a well-known example of an activator protein is the catabolite activator protein or CAP, which is involved in positive control of the lac operon.

In the regulation of gene expression, both activators and repressors are known to play important roles.[4]

Gene Regulatory Elements

Promoters resides at the beginning of the gene and serves as the site where the transcription machinery assembles and transcription of the gene begin. Enhancers turn on the promoters at specific locations, times, and levels and can be simply defined as the “promoters of the promoter.” Silencers are thought to turn off gene expression at specific time points and locations. Insulators, also called boundary elements, are DNA sequences that create cis-regulatory boundaries that prevent the regulatory elements of one gene from affecting neighboring genes. The general dogma is that these regulatory elements get activated by the binding of transcription factors, proteins that bind to specific DNA sequences, and control mRNA transcription. There could be several transcription factors that need to bind to one regulatory element in order to activate it. In addition, several other proteins, called transcription cofactors, bind to the transcription factors themselves to control transcription.[5]

See also

References

  1. ↑ "Regulatory gene - Biology-Online Dictionary". www.biology-online.org. Retrieved 2016-02-06.
  2. ↑ Campbell Biology—Concepts and Connections 7th Edition. Pearson Education. 2009. pp. 210–211.
  3. ↑ Mayer, Gene. "BACTERIOLOGY - CHAPTER NINE GENETIC REGULATORY MECHANISMS". Microbiology and Immunology Online. University of South Carolina School of Medicine. Retrieved 30 December 2012.
  4. ↑ Suzuki, David (2005). Introduction to Genetic Analysis. San Francisco: W.H. Freeman. ISBN 978-0-7167-4939-4.
  5. ↑ Ahituv, Nadav (2012). "Gene Regulatory Elements" (PDF). Gene Regulatory Sequences and Human Disease (2012). doi:10.1007/978-1-4614-1683-8. Retrieved 5 February 2016.

External links


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