The PR65 subunit of protein phosphatase 2A serves as a scaffolding molecule to coordinate the assembly of the catalytic subunit and a variable regulatory B subunit. PP2A exists in several trimeric forms, all of which consist of a core composed of a catalytic subunit associated with a 65 kDa regulatory subunit (PR65) (subunit A). The core complex associates with a third, variable subunit (subunit B), which confers distinct properties to the holoenzyme. Interacts with IPO9 (By similarity). Interacts with SGO1 (By similarity). Interacts with RAF1 (By similarity). Each HEAT repeat appears to consist of two alpha helices joined by a hydrophilic region, the intrarepeat loop. The repeat units may be arranged laterally to form a rod-like structure. Belongs to the phosphatase 2A regulatory subunit A family.