UBE2E3 and muscle atrophy: Muscle atrophy includes enhanced degradation of proteins via the autophagosome and ubiquitin-proteome system, with F-box only protein 32 (Fbxo32) and E3 ubiquitin-protein ligase TRIM63 (Trim63) ligases directing the polyubiquitination of proteins to target them for proteolysis by the 26S proteasome and the ubiquitin-mediated protein degradation pathway (59).