Involved in the regulation of endosome-to-lysosome trafficking, including endocytic trafficking of EGF-EGFR complexes and GABA-A receptors (PubMed:18675823). Involved in mitochondrial motility. When O-glycosylated, abolishes mitochondrial motility. Crucial for recruiting OGT to the mitochondrial surface of neuronal processes (PubMed:24995978). TRAK1 and RHOT form an essential protein complex that links KIF5 to mitochondria for light chain-independent, anterograde transport of mitochondria (By similarity). Interacts with RHOT1 and RHOT2 (PubMed:16630562). Found in a complex with KIF5B, OGT, RHOT1 and RHOT2 (PubMed:24995978). Interacts with HGS (PubMed:18675823). Interacts with GABRA1 (By similarity). Interacts with KIF5C (PubMed:15644324). Interacts with OGT; stable interaction is not required for glycosylation of this protein by OGT. Isoform 1 interacts with OGT (PubMed:24995978, PubMed:12435728). Predominantly associated with early endosome. The localization to early endosomes depends on its interaction with HGS/HRS (PubMed:18675823). Colocalizes with MGARP at the mitochondria (PubMed:19528298). High expression in spinal cord and moderate expression in all other tissues and specific brain regions examined. Expressed in all cell lines examined. The C-terminal region is required for the early endosomal and mitochondrial localization. O-glycosylated (PubMed:24995978, PubMed:12435728). Glycosylated by OGT; glycosylation in response to increased extracellular glucose levels is required for and leads to regulation of mitochondrial motility by OGT (PubMed:24995978). The disease is caused by variants affecting the gene represented in this entry. Over-expressed in all investigated carcinomas, especially in gastric adenocarcinoma and signet-ring carcinoma and may serve as a marker of gastric cancer. Belongs to the milton family. Extended N-terminus.