<p> In the Actinobacteria, as shown for <taxon tax_id="1773">Mycobacterium tuberculosis</taxon>, some proteins are modified by ligation between an epsilon-amino group of a lysine side chain and the C-terminal carboxylate of the ubiquitin-like protein Pup. This modification leads to protein degradation by the archaeal-like proteasome found in the Actinobacteria. Members of this protein family belong to the AAA family of ATPases and tend to be clustered with the genes for Pup, the Pup ligase PafA, and structural components of the proteasome. This protein forms hexameric rings with ATPase activity. </p>