Array-based two-hybrid assays. Bait (pGBKCg, pGBGT7g) and prey (pGADCg, pGADT7g) constructs are transformed into haploid yeast cells of opposite mating type (a and α). Preys are arrayed on selective solid medium (–L). Baits should be tested for self-activation. The Y2H screening begins with mating, in array format, of two haploid strains carrying bait and prey plasmids. Diploid cells are selected by transferring the mated array to double-dropout (–LT) followed by triple-dropout (–LTH) plates. The rectangles on the selective plate (bottom panel) mark negative and positive interactions between the bait and the prey at these specific positions of the array.