HTT
Domain
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.
Function
Huntingtin
May play a role in microtubule-mediated transport or vesicle function.
Huntingtin, myristoylated N-terminal fragment
Promotes the formation of autophagic vesicles.
Involvement in disease
Huntington disease
HD
A neurodegenerative disorder characterized by involuntary movements (chorea), general motor impairment, psychiatric disorders and dementia. Onset of the disease occurs usually in the third or fourth decade of life. Onset and clinical course depend on the degree of poly-Gln repeat expansion, longer expansions resulting in earlier onset and more severe clinical manifestations. Neuropathology of Huntington disease displays a distinctive pattern with loss of neurons, especially in the caudate and putamen.
None
The disease is caused by variants affecting the gene represented in this entry.
Lopes-Maciel-Rodan syndrome
LOMARS
An autosomal recessive neurodevelopmental disorder characterized by developmental regression in infancy, delayed psychomotor development, severe intellectual disability, and cerebral and cerebellar atrophy. Additional features include swallowing problems, dystonia, bradykinesia, and continuous manual stereotypies without chorea. Some patients manifest seizures.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
Huntingtin
Cleaved by caspases downstream of the polyglutamine stretch (PubMed:10770929, PubMed:29802276, PubMed:8696339, PubMed:9535906). The resulting N-terminal fragments are cytotoxic and provokes apoptosis (PubMed:10770929).
Huntingtin
Forms with expanded polyglutamine expansion are specifically ubiquitinated by SYVN1, which promotes their proteasomal degradation.
Huntingtin
Phosphorylation at Ser-1179 and Ser-1199 by CDK5 in response to DNA damage in nuclei of neurons protects neurons against polyglutamine expansion as well as DNA damage mediated toxicity.
Huntingtin, myristoylated N-terminal fragment
Myristoylated at Gly-551, following proteolytic cleavage at Asp-550.
Sequence Similarities
Belongs to the huntingtin family.
Tissue Specificity
Expressed in the brain cortex (at protein level). Widely expressed with the highest level of expression in the brain (nerve fibers, varicosities, and nerve endings). In the brain, the regions where it can be mainly found are the cerebellar cortex, the neocortex, the striatum, and the hippocampal formation.
Cellular localization
- Huntingtin
- Cytoplasm
- Nucleus
- Early endosome
- The mutant Huntingtin protein colocalizes with AKAP8L in the nuclear matrix of Huntington disease neurons. Shuttles between cytoplasm and nucleus in a Ran GTPase-independent manner (PubMed:15654337). Recruits onto early endosomes in a Rab5- and HAP40-dependent fashion (PubMed:16476778).
- Huntingtin, myristoylated N-terminal fragment
- Cytoplasmic vesicle
- Autophagosome
Alternative names
HD, IT15, HTT, Huntingtin, Huntington disease protein, HD protein