Fig. 7. ret1-3 α-COP cannot interact with β′-COP and is temperature-sensitive for interaction with ε-COP. Wild-type or ret1-3 mutant α-COP C-terminal halves (residues 685–1201) were expressed in the bait vector and tested for interaction with full-length β′-COP or ε-COP in the prey vector at 30 or 37°C. Results shown are from the growth assay on minimal plates lacking leucine. Note that Ret1-3p, in contrast to wild-type α-COP, does not interact with β′-COP at either temperature. Note further that Ret1-3p interacts with ε-COP at 30°C, but not at 37°C.