Category:Txn unit:lacZYA

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The lac operon is a paradigm system for transcriptional regulation. Three genes lacZ, lacY, and lacA are transcribed from the lac promoter, which is negatively regulated by Lac repressor and positively regulated by CAP-cAMP.

The lac promoter

main article:lac promoter

Mutagenesis of the lac promoter operator region[1] was used to demonstrate a method for targeting multiple mutations to a small region.

Negative regulation by Lac repressor

main article Gene Product(s)

Positive regulation by CAP-cAMP

main article Gene Product(s)

Regulation under different growth conditions

Stochastic induction in the absence of inducer

All-or-none regulation at low inducer concentrations

Catabolite repression at lac

Diaxic growth

When E. coli is grown on a mix of carbon sources, such as glucose and lactose, it will first consume the glucose and then induce expression of lacZYA to consume the lactose. This is an example of diauxie.

Inducer exclusion

See also


  1. Weiher, H & Schaller, H (1982) Segment-specific mutagenesis: extensive mutagenesis of a lac promoter/operator element. Proc. Natl. Acad. Sci. U.S.A. 79 1408-12 PubMed

Pages in category "Txn unit:lacZYA"

The following 3 pages are in this category, out of 3 total.