title: Colony Lift Colorimetric Assay for β-Galactosidase Activity.
abstract: In this protocol, we present a qualitative assay for monitoring the level of expression of β-galactosidase, an enzyme encoded by the LacZ gene, in yeast. This is useful both for determining autoactivity of LacZ expression in yeast DNA "bait" strains and for assessing LacZ reporter gene activation mediated by a transcription factor "prey" interaction with a DNA bait of interest in yeast one-hybrid (Y1H) assays. In this colorimetric assay, yeast are lysed in liquid nitrogen and then assayed for β-galactosidase expression using the colorless compound X-gal, which turns blue in the presence of this enzyme.
authors.affiliation: Program in Systems Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605.
authors.forename: Juan I
authors.initials: JI
authors.lastname: Fuxman Bass
authors.affiliation: Program in Systems Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605.
authors.forename: John S
authors.initials: JS
authors.lastname: Reece-Hoyes
authors.affiliation: Program in Systems Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605.
authors.forename: Albertha J M
authors.initials: AJ
authors.lastname: Walhout
mesh_terms: D003124:Colorimetry / Q000379:methods*; D005697:Galactosides / Q000032:analysis; D007211:Indoles / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D013194:Staining and Labeling; D020798:Two-Hybrid System Techniques; D001616:beta-Galactosidase / Q000032:analysis*
chemical_list: D005697:Galactosides; D007211:Indoles; D001616:beta-Galactosidase; C044888:5-bromo-4-chloro-3-indolyl beta-galactoside