Chromosomal integration of a binding domain:bait gene into yeast enhances detection in the two-hybrid system

We have developed a modified yeast two-hybrid system using the GAL4 transcription activator by integrating a BD:bait gene (GAL4 binding domain:bait gene) into the host chromosome. Locus-specific integration by homologous recombination and use of a strong transcription promoter enabled uniform expression of the integrated BD:bait gene in all host cells. Moreover, after introduction of an AD:prey (GAL4 activation domain:prey) plasmid, false positives were nearly undetectable and false negatives were decreased significantly. Using this improved method a cDNA library could be efficiently screened using roughly 1/10 of the materials required for conventional sequential two-hybrid screen.