UBQLN2 and amyotrophic lateral sclerosis: When we probed the purified polyQ aggregates (purified fraction confirmed in Fig 5A) with antibodies specific to proteins that are known to aggregate in the motor neurons of ALS patients (and were identified by MS in this study), we corroborated the specific presence of FUS, TDP-43, and UBQLN2 in the Htt-Q74 aggregates (Fig 5B).