I have recently been trying to use the two-hybrid yeast system (pEG202
and pJG4-5) to determine if two specific proteins interact. Unfortunately,
the results I've gotten are somewhat erratic. What I need to know is:
1. Is the Gal promoter on pJG4-5 "leaky"? Although I should only get
growth on the Gal leu- plates, I also get some growth on my Glu plates.
(Note that I have checked to make sure growth does not take place with just
the pEG202 plasmid on leu- plates, gal/raf or glucose, so this is not the
2. What is the optimum concentration of galactose/raffinose for drop
out plates? I've been using 2% galactose and 1% raffinose, as recommended
in one protocol, but this concentration appears to be inhibiting growth on
my X-GAL plates.
Many thanks in advance to anyone who can help me with these irksome details.
Dept. of Biological Sciences
University of Pittsburgh
buehler at pop.pitt.edu