Accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins (PubMed:20061386). In vitro catalyzes 'Lys-48'-linked polyubiquitination (PubMed:20061386). Involved in endoplasmic reticulum-associated degradation (ERAD) (PubMed:22607976). Required for sterol-induced ubiquitination of 3- hydroxy-3-methylglutaryl coenzyme A reductase and its subsequent proteasomal degradation (PubMed:23223569). {ECO:0000269|PubMed:20061386, ECO:0000269|PubMed:22607976, ECO:0000269|PubMed:23223569}. This is the function of Ensembl gene identifier ENSG00000184787 (UBE2G2, ubiquitin conjugating enzyme E2 G2).