Although classified as JAMM deubiquitinases in some publications, CSN6, Rpn8 and Prp8 (and their human orthologs - see PMID:17559875) lack the ability to co-ordinate Zn[2+] and are predicted to be enzymatically inactive - within MEROPS, these proteins are classed as non-peptidase homologs of the M67 family, or are not listed (http://merops.sanger.ac.uk/). All these genes are omitted from this gene group and are instead listed in the 'M67 NON-PEPTIDASE HOMOLOGS' gene group. eIF3f1, eIF3f2 and eIF3h are also classified as 'M67 non-peptidase homologs' in MEROPS, but they are included here because there is evidence that the human orthologs (EIF3F and EIF3H) exhibit deubiquitinase activity (PMID:21124883 and PMID:32269044). CSN5 has also been classed as a JAMM deubiquitinase in the literature, though it is now recognized as a deneddylase - it is included in the 'METALLO-TYPE DENEDDYLASES' gene group.