Fig. 4.

MADA and MADB interact physically. (A) Yeast 2-hybrid assays. The coding regions of the madA and madB genes were fused adjacent to the AD and BD segments of S. cerevisiae GAL4. Plasmids were cotransformed into a S. cerevisiae strain in which the GAL4 UAS regulates URA3, HIS3, and lacZ genes. Growth of strains in the absence of uracil (-ura) or histidine (-his) and increased β-galactosidase activitiy (β-gal ± SE, Miller units) indicate protein–protein interactions. (B) MADA and MADB form a complex when coexpressed in E. coli. SDS/PAGE stained with coomassie to detect proteins purified with a GST resin. Arrowheads indicate the MADA and MADB recombinant proteins (Upper). Western hybridisations with anti-MADA and anti-MADB after purification with a GST resin (Lower).