May function in signaling pathways during bone remodeling, as well as serve a broader role in cell interactions associated with differentiation in bone and testis. Associated with differentiation in bone and testis. H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate Optimum pH is 5.6. A presumed alternate transcript of 4.8-5.0 kilobases, which may lack PTP domains, is present in proliferating osteoblasts, but not detectable at other stages. Bone and testis. In the latter, restricted to the basal portion of the seminiferous tubule. Up-regulated in differentiating cultures of primary osteoblasts and down-regulated in late stage mineralizing cultures. In testis, expression is highest between stages I and VII when maturing spermatids remain buried within the Sertoli epithelium. By parathyroid hormone and cAMP analogs. The cytoplasmic domain contains potential phosphorylation sites. Belongs to the protein-tyrosine phosphatase family. Receptor class 3 subfamily.