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-terminus of the proteasomal ATPase functions 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 (Probable). Is also able to cleave other nucleoside triphosphates including GTP and TTP, but the rate of hydrolysis is 4- to 5-fold slower than for ATP. ATPase activity is inhibited by EDTA in vitro. Optimum temperature is 42 degrees Celsius. ATPase activity is 1.5-fold decreased at 25 degrees Celsius and 37 degrees Celsius, 4.7-fold at 20 degrees Celsius. The protein is not active at 50 degrees Celsius. Homododecamer, in a proposed two stacked hexameric ring configuration, but may also form homohexamer. The hexameric complex has likely 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 probably interacts with the alpha-rings of the proteasome core by binding to the intersubunit pockets. Interacts with SAMP1-MoaE conjugate in vitro, but does not bind to SAMP1 or MoaE alone (PubMed:24343376). Interacts with NcsA (PubMed:24906001). Up-regulated at the mRNA level during transition from exponential to stationary phase. However, at the protein level, PanA is expressed at a high and relatively constant level throughout growth. 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. Strains lacking panA gene alone display relatively normal growth rate and overall cell yield, but they are more sensitive to growth on organic versus inorganic nitrogen sources and hypo-osmotic stress, they show limited growth in the presence of L-canavanine and display enhanced thermotolerance. Moreover, strains lackings both panA and panB still show robust growth, demonstrating that the PAN proteins are not essential. The biochemical properties of PAN 1 are highly dependent on molar concentrations of salt with a significant loss of ATPase activity and complex dissociation detected at 0.75 M NaCl. Belongs to the AAA ATPase family. Truncated N-terminus.