I am glad to hear some of you doing fine with lacZ assay in 2-Hybrid
system. My problem is just the opposite. I did a 2 Hy. screen of 500.000
clones using Gal4 system and found about 80 positive (i.e. His+) clones.
checking them in lacZ assay I failed to detect blue clones at all. My controls
(p53, pSV40 interacting controls from Stratagene) do work fine. In another
screen (different bait) I found only one of 12 His+ clones turning blue in the
My question: Did someone have similar problems? Any idea why this may happen?