Huntingtin 

Huntingtin (HTT) is a soluble 3144 amino acid (348 kDa) protein, with the highest levels of expression being found in the CNS and testes. An abnormal expansion of a glutamine stretch (polyQ) in N-terminal sequence of huntingtin leads to the devastating neurodegenerative disorder Huntington's disease (HD). Subcellular fractionation and microscopic studies have shown that huntingtin is associated with vesicles and microtubules by interacting with huntingtin-associated protein 1 (HAP1), which is reported to form a complex with the dynactin and modulate or regulate the dynein–dynactin complex. There is evidence that huntingtin participates in post-Golgi trafficking of proteins that follow the regulated secretory pathway.