Enables cell adhesion molecule binding activity and signaling receptor binding activity. Involved in several processes, including heterophilic cell-cell adhesion via plasma membrane cell adhesion molecules; nervous system development; and regulation of synapse assembly. Acts upstream of or within negative regulation of receptor signaling pathway via JAK-STAT and regulation of immune response. Located in glutamatergic synapse and hippocampal mossy fiber to CA3 synapse. Is integral component of presynaptic membrane. Is active in Schaffer collateral - CA1 synapse. Is expressed in several structures, including alimentary system; genitourinary system; nervous system; respiratory system; and sensory organ. Orthologous to human PTPRD (protein tyrosine phosphatase receptor type D). [provided by Alliance of Genome Resources, Apr 2022]