The function of UBE2Z (ubiquitin conjugating enzyme E2 Z, Ensembl gene identifier ENSG00000159202) is as follows. Catalyzes the covalent attachment of ubiquitin to other proteins (By similarity). Specific substrate for UBA6, not charged with ubiquitin by UBE1. May be involved in apoptosis regulation. {ECO:0000255|PROSITE-ProRule:PRU00388, ECO:0000269|PubMed:17464193, ECO:0000269|PubMed:17597759}.