Enables protein tyrosine phosphatase activity. Involved in regulation of postsynaptic density assembly; regulation of presynapse assembly; and synaptic membrane adhesion. Is integral component of postsynaptic density membrane and integral component of synaptic vesicle membrane. Is active in glutamatergic synapse. Is integral component of presynaptic membrane. Orthologous to human PTPRS (protein tyrosine phosphatase receptor type S). [provided by Alliance of Genome Resources, Apr 2022]