[Huntington disease].

The gene responsible for Huntington's disease produces a protein with a molecular weight of about 350k, designated huntingtin. We identified both wild-type and mutant huntingtin in the brain and lymphoblastoid cells. Although the function of huntingtin is still unknown, several associated proteins such as HAP1, Ubiquitin-conjugating enzyme, HIP1 and glyceraldehyde-3-phosphate-dehy dorogenase (GAPDH) were reported. We found the huntingtin can associate in vitro with microtubules. Through the process of assembly and disassembly of microtubules, both wild-type and mutant huntingtin associate with microtubules to almost the same degree. The results suggest that huntingtin may have a role in intracellular organelle transport or axonal transport by its association with microtubules. The functional disturbance by expanded polyglutamine stretch may modify the feature of the disease.