Transcription factor that mediates regulation of both acid- and alkaline-expressed genes in response to ambient pH. At alkaline ambient pH, activates transcription of alkaline-expressed genes (including pacC itself) and represses transcription of acid-expressed genes. Specifically recognizes and binds the consensus sequence 5'-GCCARG-3'. Required for virulence in invasive pulmonary aspergillosis (IPA). Binds to DNA. Interacts with palA, which binds to the two YPX[LI] motifs and is required for proteolytic processing. Cytoplasmic at acidic ambient pH, and nuclear in its processed form at alkaline ambient pH. By alkaline conditions. Only zinc fingers 2 and 3 contact DNA. Zinc finger 1 interacts with zinc finger 2. Interacting regions A, B and C form intramolecular interactions in the full-length translation product at acidic ambient pH, keeping the protein in a 'closed' conformation preventing proteolytic cleavage by the processing protease. Activated by C-terminal proteolytic cleavage. At neutral to alkaline ambient pH, the signaling protease (probably palB) cleaves pacC within the conserved 24-residue signaling protease box, removing the C-terminal interacting region C and producing a 53 kDa 'open' conformation intermediate protein, which is committed to further processing. In an ambient pH-independent reaction, the processing protease (probably the proteasome) removes additional C-terminal residues to yield the 27 kDa functional form. Belongs to the pacC/RIM101 family. Met-5 is the major initiator, but Met-1 may also be used.