ATPase which is responsible for recognizing, binding, unfolding and translocation of substrate proteins into the archaeal 20S proteasome core particle. Is essential for opening the gate of the 20S proteasome via an interaction with its C-terminus, thereby allowing substrate entry and access to the site of proteolysis. Thus, the C-termini of the proteasomal ATPase function like a 'key in a lock' to induce gate opening and therefore regulate proteolysis. Unfolding activity requires energy from ATP hydrolysis, whereas ATP binding alone promotes ATPase-20S proteasome association which triggers gate opening, and supports translocation of unfolded substrates. Homohexamer. The hexameric complex has a two-ring architecture resembling a top hat that caps the 20S proteasome core at one or both ends. Upon ATP-binding, the C-terminus of PAN interacts with the alpha-rings of the proteasome core by binding to the intersubunit pockets. Consists of three main regions, an N-terminal coiled-coil domain that may assist in substrate recognition, an interdomain involved in PAN hexamerization, and a C-terminal ATPase domain of the AAA type. Belongs to the AAA ATPase family. Extended N-terminus.