Possesses tyrosine phosphatase activity. Plays a role in regulating the glomerular pressure/filtration rate relationship through an effect on podocyte structure and function. H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate Interacts (phosphorylated form) with FYN and GRB2. Modification of podocyte structure such that the normal octopoid podocyte is simplified to a more amoeboid structure and that the foot processes are shorter and broader than normal. These changes are associated with altered distribution of the podocyte intermediate cytoskeletal protein vimentin/VIM. Mutant animals have a reduced glomerular filtration rate and reduced glomerular nephrin (NPHS1) content. However, there is no evidence of proteinuria. After removal of one or more kidneys, Ptpro-null animals have higher blood pressure than does their wild-type littermates. Belongs to the protein-tyrosine phosphatase family. Receptor class 3 subfamily.