Regulatory subunit of protein phosphatase 6 (PP6). May function as a scaffolding PP6 subunit. May have an important role in maintaining immune self-tolerance (By similarity). Protein phosphatase 6 (PP6) holoenzyme is proposed to be a heterotrimeric complex formed by the catalytic subunit, a SAPS domain-containing subunit (PP6R) and an ankyrin repeat-domain containing regulatory subunit (ARS). Interacts with PPP6C and ANKRD28 (By similarity). Strongest expression observed in lung, spleen, bladder and liver and weaker levels present in brain, heart, kidney, skeletal muscle and pancreas. Belongs to the SAPS family. Extended N-terminus.