Lac repressor

From The School of Biomedical Sciences Wiki
Jump to: navigation, search

The lacI repressor protein, with the help of an inducer, binds to the lacO operator in order to prevent the expression of genes that would lead to the metabolism of lactose in the cell. The repressor- inducer complex achieves this by binding to the DNA at the lacO operon[1]. The specific condition to when the lac repressor binds to the lacO operator is when there is no lactose. As when lactose is present, an inducer molecule binds to the lac repressor causing an confirmational change in shape, preventing it from binding to the DNA causing no repression. Hence transcription continues for the production of lac mRNA[2].


  1. Hartl, D and Ruvolo, M (2012). Genetics analysis of genes and genomes. 8th ed. USA: Jones and Barlett learning. p394-395.
  2. Berg JM, Tymoczko JL, Stryer L, Web NCD, Stryer, Clarke ND. Biochemistry (chapters 1-34). 5th ed. New York, NY: W.H.Freeman & Co; 2002 Feb 15. ISBN: 9780716730514. p1284-1290.

Personal tools