Enables protein serine/threonine phosphatase activity. Acts upstream of or within protein dephosphorylation. Is expressed in dorsal root ganglion; lower jaw molar; telencephalon mantle layer; trigeminal ganglion; and upper jaw molar. Orthologous to human PPM1J (protein phosphatase, Mg2+/Mn2+ dependent 1J). [provided by Alliance of Genome Resources, Apr 2022]