This entry represents the first region of HEAT repeats from Huntingtin (Htt), which is part of the N-terminal HEAT domain [2]. It is separated from the rest of the domain (Pfam:PF12372) by an unstructured region. Htt is expressed in many tissues with various expression levels and is involved in a number of cellular functions. However, its exact function is not yet clear. An abnormal polyglutamine (polyQ) expansion between 1-90aa at the very N-terminal causes Huntington's disease (HD), a progressive autosomal-dominant neurodegenerative disease characterised by an uncontrolled motor movement known as chorea, cognitive disorder and depression [1]. Htt consists of multiple HEAT repeats organised in N-terminal, bridge and C-terminal domains [1], which function as a scaffold that mediated interactions with binding partners.

1: The cryo-electron microscopy structure of huntingtin. Guo Q, Bin Huang, Cheng J, Seefelder M, Engler T, Pfeifer G, Oeckl P, Otto M, Moser F, Maurer M, Pautsch A, Baumeister W, Fernandez-Busnadiego R, Kochanek S; Nature. 2018;555:117-120. PMID:29466333

2: The Polyglutamine Expansion at the N-Terminal of Huntingtin Protein Modulates the Dynamic Configuration and Phosphorylation of the C-Terminal HEAT Domain. Jung T, Shin B, Tamo G, Kim H, Vijayvargia R, Leitner A, Marcaida MJ, Astorga-Wells J, Jung R, Aebersold R, Peraro MD, Hebert H, Seong IS, Song JJ; Structure. 2020;28:1035-1050. PMID:32668197