Transcription factor that acts as a master regulator of lysosomal biogenesis and immune response (PubMed:2338243, PubMed:29146937, PubMed:30733432, PubMed:31672913). Specifically recognizes and binds E-box sequences (5'-CANNTG-3'); efficient DNA-binding requires dimerization with itself or with another MiT/TFE family member such as TFEB or MITF (By similarity). Involved in the cellular response to amino acid availability by acting downstream of MTOR: in the presence of nutrients, TFE3 phosphorylation by MTOR promotes its cytosolic retention and subsequent inactivation (PubMed:31672913). Upon starvation or lysosomal stress, inhibition of MTOR induces TFE3 dephosphorylation, resulting in nuclear localization and transcription factor activity (PubMed:31672913). Maintains the pluripotent state of embryonic stem cells by promoting the expression of genes such as ESRRB; mTOR-dependent TFE3 cytosolic retention and inactivation promotes exit from pluripotency (By similarity). Required to maintain the naive pluripotent state of hematopoietic stem cell; mTOR-dependent cytoplasmic retention of TFE3 promotes the exit of hematopoietic stem cell from pluripotency (PubMed:30733432). TFE3 activity is also involved in the inhibition of neuronal progenitor differentiation (By similarity). Acts as a positive regulator of browning of adipose tissue by promoting expression of target genes; mTOR-dependent phosphorylation promotes cytoplasmic retention of TFE3 and inhibits browning of adipose tissue (By similarity). In association with TFEB, activates the expression of CD40L in T-cells, thereby playing a role in T-cell-dependent antibody responses in activated CD4(+) T-cells and thymus-dependent humoral immunity (By similarity). Specifically recognizes the MUE3 box, a subset of E-boxes, present in the immunoglobulin enhancer (PubMed:2338243). It also binds very well to a USF/MLTF site (PubMed:2338243). May regulate lysosomal positioning in response to nutrient deprivation by promoting the expression of PIP4P1 (PubMed:29146937). Homodimer and heterodimer; with TFEB or MITF. Interacts with RRAGC/RagC GDP-bound and RRAGD/RagD GDP-bound (By similarity). When nutrients are present, phosphorylation by MTOR prevents nuclear translocation and activity (PubMed:22692423, PubMed:30733432). Conversely, inhibition of mTORC1, starvation and lysosomal disruption, promotes dephosphorylation and translocation to the nucleus (PubMed:22692423, PubMed:30733432). Ubiquitous in fetal and adult tissues. Sumoylated; does not affect dimerization with MITF. Phosphorylation by MTOR regulates its subcellular location and activity (PubMed:21209915, PubMed:30733432). When nutrients are present, phosphorylation by MTOR promotes retention in the cytosol (PubMed:30733432). Inhibition of mTORC1, starvation and lysosomal disruption, promotes dephosphorylation and translocation to the nucleus (PubMed:30733432). The disease is caused by variants affecting the gene represented in this entry. A chromosomal aberration involving TFE3 is found in patients with alveolar soft part sarcoma. Translocation t(X;17)(p11;q25) with ASPSCR1 forms a ASPSCR1-TFE3 fusion protein. Chromosomal aberrations involving TFE3 are found in patients with papillary renal cell carcinoma. Translocation t(X;1)(p11.2;q21.2) with PRCC; translocation t(X;1)(p11.2;p34) with PSF; inversion inv(X)(p11.2;q12) that fuses NONO to TFE3. Belongs to the MiT/TFE family.