FIG 4.

Dominant impairment of [URE3] by some mutant Ure2 proteins depends on Btn2 and Cur1. Wild type (wt), btn2Δ cur1 double mutant, and single btn2Δ and cur1Δ mutants (third and fourth rows) propagating [URE3] composed of wild-type Ure2 were transformed by plasmids (pEAD31-34) encoding the galactose-inducible Ure2 mutants indicated at the top. Transformants were grown in SGal-leu for 8 h and then plated on 1/2YPD. The frequency of red transformant colonies reflects how efficiently the mutant proteins destabilize endogenous [URE3].