The results obtained indicate that PcACE1 transactivation domain is located in the carboxy terminal half and contains an array of cysteines in the form of Cys-X-Cys and Cys-chi(2)-Cys and a 60% of Ser. Therefore, these results show that this type of Cys motif can function as transcription activating domain not only in transcription factors that respond to minimal copper concentrations but also in those that respond to high copper concentrations. This is the first transactivation domain reported in a basidiomycete fungus.