Catalyzes the covalent attachment of ubiquitin to other proteins. Seems to function in the selective degradation of misfolded membrane proteins from the endoplasmic reticulum (ERAD) (By similarity). In cooperation with the GATOR2 complex, catalyzes 'Lys-6'- linked ubiquitination of NPRL2 (PubMed:36528027). . This is the function of Ensembl gene identifier ENSG00000160087 (UBE2J2, ubiquitin conjugating enzyme E2 J2).