Lysine 117 on ataxin-3 modulates toxicity in

Ataxin-3 (Atxn3) is a deubiquitinase with a polyglutamine (polyQ) repeat tract whose abnormal expansion causes the neurodegenerative disease, Spinocerebellar Ataxia Type 3 (SCA3; also known as Machado-Joseph Disease). The ubiquitin chain cleavage properties of Atxn3 are enhanced when it is ubiquitinated at lysine (K) at position 117. K117-ubiqutinated Atxn3 cleaves poly-ubiquitin more rapidly in vitro compared to its unmodified counterpart and this residue is also important for Atxn3 roles in cell culture and in