UBR4 and Alzheimer disease: This observation confirms the importance of the ubiquitin–proteasome system in a context of defective protein clearance and protein accumulation [56, 61], while highlighting some of its key members consistently observed among pTau interactors in the AD brain, such as: SQSTM1 (also known as p62), which is involved in the shuttle of polyubiquitinated Tau for proteasomal degradation; ubiquitin/polyubiquitin precursors such as RPS27A and UBC; ubiquitin protein ligases such as ARMC8 and UBR4; several members of the PSMC and PSMD families constituting the proteasome [5, 10, 26, 60].