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AAT Bioquest

How does lacZ staining work?

Posted February 13, 2020


Answer

LacZ is a frequently used reporter gene, encoding for the protein beta-galactosidase in cultured cells, which appear blue when the cultured cells are grown on a medium containing X-gal analog.

  • The staining solution is made of X-gal (200 mg/ml), MgCl2 (1M), K ferri-cyanide (50mM), K ferro-cyanide (50mM), and PBS.
  • The cells are then fixated in formaldehyde/methanal (37 %), glutaraldehyde (25 %), and PBS.

The steps for lacZ staining are:

  1. Wash cells in PBS
  2. Add fixative solution
  3. Incubate for 2 minutes
  4. Wash 3 times with PBS
  5. Add staining solution
  6. Incubate overnight at 37°C