A reliable lacZ expression reporter cassette for multipurpose, knockout-first alleles

Genesis. 2004 Mar;38(3):151-8. doi: 10.1002/gene.20012.


Alteration of the mouse genome through homologous recombination in embryonic stem (ES) cells is the most accurate and versatile way to dissect gene function in a vertebrate model. Most often, a selectable marker is used to create a knockout allele by replacing an essential part of the gene. However, knockout strategies are limited because the mutation is present constitutively. Conditional approaches based on the Cre-loxP site-specific recombination (SSR) system address this limitation; however, it requires that all parts of the targeted gene remain in ES cells. Here we report success with a "knockout-first" strategy that ablates gene function by insertion of RNA processing signals without deletion of any of the target gene. Incorporation of site-specific recombination target sites creates a multipurpose allele for both knockout and conditional applications.

MeSH terms

  • Animals
  • Carrier Proteins / genetics
  • DNA-Binding Proteins / genetics
  • Fatty Acid Transport Proteins
  • Female
  • Gene Silencing*
  • Genes, Reporter
  • Genetic Engineering / methods
  • Genetic Vectors*
  • Integrases / genetics*
  • Integrases / metabolism
  • Lac Operon / physiology*
  • Membrane Proteins / genetics
  • Membrane Transport Proteins*
  • Mice
  • Mice, Knockout
  • Nuclear Proteins / genetics
  • RNA* / genetics
  • RNA* / metabolism
  • Recombination, Genetic*
  • Thioredoxins / genetics
  • Transfection


  • Aff1 protein, mouse
  • Carrier Proteins
  • DNA-Binding Proteins
  • Fatty Acid Transport Proteins
  • Membrane Proteins
  • Membrane Transport Proteins
  • Nuclear Proteins
  • Slc27a4 protein, mouse
  • Txn2 protein, mouse
  • Thioredoxins
  • RNA
  • Cre recombinase
  • Integrases