Transcription factor EC is a protein that in humans is encoded by the TFEC gene. 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 (By similarity). Collaborates with MITF in target gene activation (By similarity). Acts as a transcriptional repressor on minimal promoter containing mu E3 enhancer sequence (By similarity). Binds to mu E3 DNA sequence of the immunoglobulin heavy-chain gene enhancer (By similarity). Binds DNA in a homo- or heterodimeric form.