Transcription factor that regulates the expression of genes with essential roles in cell differentiation, proliferation and survival. Binds to M-boxes (5'-TCATGTG-3') and symmetrical DNA sequences (E-boxes) (5'-CACGTG-3') found in the promoters of target genes, such as BCL2 and tyrosinase (TYR). Plays an important role in melanocyte development by regulating the expression of tyrosinase (TYR) and tyrosinase-related protein 1 (TYRP1). Plays a critical role in the differentiation of various cell types, such as neural crest-derived melanocytes, mast cells, osteoclasts and optic cup-derived retinal pigment epithelium. Homodimer or heterodimer; dimerization is mediated via the coiled coil region (By similarity). Efficient DNA binding requires dimerization with another bHLH protein (By similarity). Binds DNA in the form of homodimer or heterodimer with either TFE3, TFEB or TFEC (By similarity). Identified in a complex with HINT1 and CTNNB1 (By similarity). Interacts with KARS1 (By similarity). Interacts with VSX2 (By similarity). Found exclusively in the nucleus upon phosphorylation. The leucine zipper region is part of a larger coiled coil. Phosphorylation at Ser-405 significantly enhances the ability to bind the tyrosinase promoter (By similarity). Phosphorylated at Ser-180 and Ser-516 following KIT signaling, triggering a short live activation: Phosphorylation at Ser-180 and Ser-516 by MAPK and RPS6KA1, respectively, activate the transcription factor activity but also promote ubiquitination and subsequent degradation by the proteasome (By similarity). Phosphorylated in response to blue light (415nm) (By similarity). Ubiquitinated following phosphorylation at Ser-180, leading to subsequent degradation by the proteasome. Deubiquitinated by USP13, preventing its degradation. Osteopetrotic rat of unknown genetic defect microphthalmia-blanc (mib) has been described whose skeletal sclerosis improves dramatically with age and that is associated with pigmentation defects. Mib at the homozygous state shows absence of skin and fur pigmentation, small eyes, and defects of incisor tooth eruption. Belongs to the MiT/TFE family.