Transcriptional regulator that acts as a repressor or an activator. Acts as a transcriptional repressor on minimal promoter containing element F (that includes an E-box sequence). Binds to element F in an E-box sequence-specific manner. Acts as a transcriptional transactivator on the proximal promoter region of the tartrate-resistant acid phosphatase (TRAP) E-box containing promoter. Collaborates with MITF in target gene activation. Acts as a transcriptional repressor on minimal promoter containing mu E3 enhancer sequence. Binds to mu E3 DNA sequence of the immunoglobulin heavy-chain gene enhancer. Binds DNA in a homo- or heterodimeric form (By similarity). Homodimer. Forms heterodimers with MITF and TFE3. Interacts with MITF (By similarity). Belongs to the MiT/TFE family.