Involved in the regulation of endosome-to-lysosome trafficking, including endocytic trafficking of EGF-EGFR complexes and GABA-A receptors (By similarity). Involved in mitochondrial motility (PubMed:24995978). When O-glycosylated, abolishes mitochondrial motility. Crucial for recruiting OGT to the mitochondrial surface of neuronal processes (By similarity). 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. Found in a complex with KIF5B, OGT, RHOT1 and RHOT2. Interacts with HGS (By similarity). Interacts with GABRA1 (PubMed:16380713). Interacts with KIF5C. Interacts with OGT; stable interaction is not required for glycosylation of this protein by OGT. Isoform 1 interacts with OGT (By similarity). Predominantly associated with early endosome. The localization to early endosomes depends on its interaction with HGS/HRS. Colocalizes with MGARP at the mitochondria. Widely expressed with the greatest expression in brain, liver and kidney. Detected throughout the CNS, including the cortex, hippocamps, thalamus and various subcortical nuclei of the forebrain and midbrain, the granule of Purkinje layers of the cerebellum and the gray matter of the spinal cord. High level detected in lower moter neurons (at protein level). O-glycosylated (PubMed:24995978). Glycosylated by OGT; glycosylation in response to increased extracellular glucose levels is required for and leads to regulation of mitochondrial motility by OGT (By similarity). A spontaneous mutation (hyrt mice) causes a recessively transmitted form of hypertonia neurological dysfunction characterized by postural abnormalities, jerky movements and tremormutant. Hyrt mice have much lower levels of GABA(A) receptors in the CNS, particularly the lower motor neurons, than do wild-type mice, indicating that the hypertonicity of the mutants is likely to be caused by deficits in GABA-mediated motor neuron inhibition. Belongs to the milton family.