May have a role in the recovery or adaptation response of photoreceptors. May have a role in development. H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 2 manganese ions per subunit. Activated by calcium. Optimum pH is 8.0. Detected in retina and retinal derived Y-79 retinoblastoma cells. Also found in fetal brain. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. May have no functional significance. Belongs to the PPP phosphatase family.