Fungal-specific basic helix-loop-helix (bHLH) transcription factor involved in the activation of the dihydroxynaphthalene (DHN)-melanin pathway (PubMed:27393422). Specifically recognizes DNA binding sites (E-boxes) identified in the promoter sequence of the gene coding for the polyketide synthase pksP (PubMed:27393422). Localization to the nucleus is increased by external KCl. Expression is inceased 10 to 15 fold when the MAPK mpkB is deleted. Affects sporulation and reduces the expression of the DHN-melanin gene cluster. Belongs to the MAX family.