<p> This entry describes a protein family of unknown function, about 690 residues in length, in which some members show C-terminal sequence similarity to <db_xref db="INTERPRO" dbkey="IPR008269"/>, which is the Lon protease C-terminal proteolytic domain, from MEROPS family S16. However, the annotated catalytic sites of <taxon tax_id="562">Escherichia coli</taxon> Lon protease are not conserved in members of this family. Members have a motif GP[RK][GS]TGKS, similar to the ATP-binding P-loop motif GxxGxGK[ST].</p>