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. Regulatory subunit 3 (R3) of the histone H2A phosphatase complex (HTP-C) consisting of PPH3, PSY2 and PSY4. Interacts with SPT4, SPT5 and TIP41. Present with 7010 molecules/cell in log phase SD medium.