Fig. 7. Yeast two-hybrid analysis of CudA homodimerisation. The CudA prey is constitutively expressed and in the presence of galactose as an inducer (in Gal+ medium) the bait is also expressed. The test bait is CudA and the STATa SH2 domain is used as a negative control bait. Because there is an interaction between bait and prey, i.e. homodimerisation of CudA, lacZ expression is activated and is detected with X-Gal. Staining was for 3 days at 30°C. The same bait and prey combinations were tested by growth selection using a leu marker and gave identical results (data not shown).