The 26S protease is involved in the ATP-dependent degradation of ubiquitinated proteins. The regulatory (or ATPase) complex confers ATP dependency and substrate specificity to the 26S complex (PubMed:22158466). Acts redundantly with RPT2A in the regulation of gametogenesis (PubMed:21784786, PubMed:22158466). With RPT2A plays a critical role in 26S proteasome assembly (PubMed:22158466). Component of the 19S regulatory particle (RP/PA700) base subcomplex of the 26S proteasome. The 26S proteasome is composed of a core protease (CP), known as the 20S proteasome, capped at one or both ends by the 19S regulatory particle (RP/PA700). The RP/PA700 complex is composed of at least 17 different subunits in two subcomplexes, the base and the lid, which form the portions proximal and distal to the 20S proteolytic core, respectively. Preferentially expressed in the root and shoot apical meristem. No visible phenotype under normal growth conditions (PubMed:22158466). The double mutants rpt2a and rpt2b are blocked in both male and female gametogenesis (PubMed:22158466, PubMed:21784786). Belongs to the AAA ATPase family.