Fig. 2.

mAb 4C3 decreases phosphatase activity. Top: Western blotting was performed on glomerular protein using mAbs to PTPro (P8E7 and 4C3), podocalyxin (4B3), and control (BB5). The anti-PTPro Abs precipitated comparable amounts of PTPro, as shown by the arrows. The blot on the left was developed with 4C3 to identify PTPro. The blot on the right was developed with BB5. The bottom molecular weight bands are seen on both the left and right and show the heavy chains of the mAbs used for immunoprecipitation. Bottom: phosphatase activity of the immunoprecipitates was measured using the p-nitrophenylphosphate assay. Also shown are units of phosphatase activity developed from a standard curve made using recombinant rabbit PTPro intracellular domain. The 4C3 immunoprecipitate contains approximately half the phosphatase activity of the P8E7 immunoprecipitate.