The yeast two-hybrid system is to clone (fuse) the two proteins to be studied into the DNA-binding domain (DNA-BD) and transcriptional activation domain of the yeast expression plasmid (such as GAL4, etc.) On the domain (AD), a fusion expression vector is constructed to analyze the interaction between the two proteins from the expression product. Blue-white spot screening is a method of recombinant screening, which screens recombinants based on the genetic characteristics of the vector.

Blue and white spot screening mainly involves gene complementation and antibiotic genes. Blue and white spots are screened on the indicator medium. The colonies without transformed plasmid cannot grow due to lack of antibiotic resistance. The colonies with recombinant plasmid are white and the colonies with non-recombinant plasmid are blue. Recombinant clones are screened directly based on the different colors. method.