For detection of ß-Galactosidase in immunohistochemical and clone expression applications.

IPTG (Isopropyl-ß-D-thiogalactopyranoside) may be used to maximize the expression of genes in expression vectors. When screening a lambda bacteriophage library with an antibody, the probability of success can be increased by preventing the expression of the fusion protein until the plaques are well established. By placing a nitrocellulose filter containing the inducer IPTG onto the plate and continuing growth at 37°C, the expression of the potential ß-galactosidase-cDNA fusion protein can be induced after 3-4 hours of plaque growth. The nitrocellulose filter then is screened with antibodies. IPTG is also used in combination with X-Gal to detect active ß-galactosidase, and it is practical in applications using Bacteriophage M13 and Igt11 vectors. (1)