In all of these viruses the AlkB domain is a part of the replicase polyprotein, which normally consists of a viral Other Pfam domains -Peptidase_C21, C23, C33, C34, C35 and C41, A1pp and OTU -were also identified in subsets of sequences. A1pp is a member of the Appr-1-p processing enzyme family, and the domain is found in a number of otherwise unrelated proteins, including non-structural proteins of several types of ssRNA viruses. OTU is a mem-ber of a family of cysteine proteases that are homologous to the ovarian tumour (otu) gene in Drosophila. Members of this family are found in Eukaryotes, viruses and pathogenic bacteria.