This model describes a protein family of unknown function, about 690 residues in length, in which some members show C-terminal sequence similarity to pfam05362, which is the Lon protease C-terminal proteolytic domain, from MEROPS family S16. However, the annotated catalytic sites of E. coli 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]. [Hypothetical proteins, Conserved]