May play a role in microtubule-mediated transport or vesicle function. Promotes the formation of autophagic vesicles. Interacts with PFN1 (By similarity). Interacts through its N-terminus with PRPF40A (By similarity). Interacts with PQBP1 (By similarity). Interacts with SETD2 (By similarity). Interacts with SH3GLB1 (PubMed:12456676). Interacts with SYVN (By similarity). Interacts with TPR; the interaction is inhibited by forms of Huntingtin with expanded polyglutamine stretch (By similarity). Interacts with ZDHHC13 (via ANK repeats) (PubMed:26198635). Interacts with ZDHHC17 (via ANK repeats) (PubMed:26198635). 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. The highest level is seen throughout the brain, but it is also found in the stomach, heart, testis, adipose tissue, muscle, spleen, liver, and kidney. Predominant expression in neuronal tissues at all developmental stages. In 14.5 day old embryos, it is also detected in non-neuronal tissues. This expression is down-regulated in later stages of development. 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-1159 and Ser-1179 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-530, following proteolytic cleavage at Asp-529. The poly-Gln region does not appear to be polymorphic, explaining the absence of a murine HD-like disorder (PubMed:8009370). Cannot be explained by a simple splicing event. Belongs to the huntingtin family.