May play a role in microtubule-mediated transport or vesicle function. Promotes the formation of autophagic vesicles. Interacts with PFN1. Interacts through its N-terminus with PRPF40A. Interacts with PQBP1. Interacts with SETD2. Interacts with SH3GLB1. Interacts with SYVN. Interacts with TPR; the interaction is inhibited by forms of Huntingtin with expanded polyglutamine stretch. Interacts with ZDHHC13 (via ANK repeats). Interacts with ZDHHC17 (via ANK repeats). Interacts with F8A1/F8A2/F8A3 (By similarity). Found in a complex with F8A1/F8A2/F8A3, HTT and RAB5A; mediates the recruitment of HTT by RAB5A (By similarity). Shuttles between cytoplasm and nucleus in a Ran GTPase-independent manner. Expressed to a high degree in all the regions of the brain of adults and in meiotic cells of the testis. In addition, very low levels are detected in various non-neuronal tissues (heart, muscle, liver, lung and kidney). Identified at high levels in neuronal tissues of embryos as early as day 14.5. This expression remains constant in all further development stages (up to the adult). On the other hand the expression in non-neuronal tissues is down-regulated from stage 17.5 day old embryos. The N-terminal Gln-rich and Pro-rich domain has great conformational flexibility and is likely to exist in a fluctuating equilibrium of alpha-helical, random coil, and extended conformations. Phosphorylation at Ser-1150 and Ser-1170 by CDK5 in response to DNA damage in nuclei of neurons protects neurons against polyglutamine expansion as well as DNA damage mediated toxicity. Cleaved by caspases downstream of the polyglutamine stretch. Myristoylated at Gly-522, following proteolytic cleavage at Asp-521. The poly-Gln region does not appear to be polymorphic, explaining the absence of a rodent HD-like disorder. Belongs to the huntingtin family.