Questioning the Ubiquity of Neofunctionalization
Figure 3
Shortcomings of the yeast two-hybrid assay.
(A) The traditional view of the yeast two-hybrid assay. A bait protein is hybridized with the GAL4 binding domain which binds to the upstream activation sequence for galactose (UASG). A prey protein hybridized with the GAL4 activation domain interacts with the bait protein. The complex forms a functional transcriptional activator and the downstream reporter gene is expressed. (B) A more accurate view of yeast two-hybrid assay. The GAL4 binding domain actually binds to UASG as a dimer. (C) If the GAL4 binding domain is hybridized to a self-interacting protein, self-interacting protein bait dimerizations would reduce the probability of bait-prey interactions.