Since polyQ-expanded ataxin-3 retains its neuroprotective capacity in Drosophila [162] and ubiquitination of ataxin-3 enhances its activity, Todi et al. [90] propose that ubiquitination of polyQ-expanded ataxin-3 may serve a neuroprotective function in MJD mice and increased catalytic activity would enhance this neuroprotective function [103]. Here, ATXN3 is linked to Machado-Joseph disease.