Huntingtin (HTT) is a large soluble protein composed of approximately 3144 amino acids, with a molecular weight of around 348 kDa. It is highly expressed in the central nervous system, particularly in neurons of the cerebral cortex and hippocampus. Huntingtin plays crucial roles in various cellular processes, including clathrin-mediated endocytosis, axonal transport, and synaptic signal transduction. It also helps protect neurons from apoptosis.