Core regulatory subunit of the histone H2A phosphatase complex, which dephosphorylates H2AS128ph (gamma-H2A) that has been displaced from sites of DNA lesions in the double-stranded DNA break repair process. Dephosphorylation is necessary for efficient recovery from the DNA damage checkpoint (By similarity). Regulatory subunit 3 (R3) of the histone H2A phosphatase complex (HTP-C) consisting of PPH3, PSY2 and PSY4.