Podocyte Protein, Nephrin, Is a Substrate of Protein Tyrosine Phosphatase 1B

Figure 3

PTP1B and PTP-PEST, but not SHP2, inhibit fyn-induced nephrin phosphorylation. Cos-1 cells were transiently transfected with the indicated plasmids and cell lysates were analyzed after 24 hrs by immunoprecipitation/immunoblotting. When expressed alone, tyrosine phosphorylation of nephrin was weak, which was markedly increased by fyn. PTP1B and PTP-PEST inhibited fyn-induced tyrosine phosphorylation of nephrin, while SHP2 did not have any impact. TL: total lysates. PTP1B and PEP-PEST were tagged with GST. WT indicates wild type. DA and CS indicate substrate trapping (catalytically inactive) mutants of PTP1B and PTP-PEST, respectively (see Section 2).