FIG 4.

Nephrin phosphorylation is attenuated when nephrin Y1154 (Y3) and Y1172 (Y4) residues are mutated. (A) Nephrin phosphorylation following CD16-nephrin clustering was markedly attenuated when a CD16⁻ nephrin construct carrying the Y3,4F mutation was transfected along with Shp2. Similarly, there was attenuation of Shp2 Y542 and Src Y416 phosphorylation following clustering of CD16-nephrin chimeras carrying the Y3,4F (double) mutations. (B) Quantification of bands using densitometry showed a statistically significant increase in nephrin phosphorylation in the presence of Shp2 compared to the control at each time point (*, P < 0.001; **, P < 0.01; NS, not significant using the ANOVA test). The decrease in nephrin phosphorylation following clustering of mutant CD16-nephrin (Y3,4F) in the presence of Shp2 was also statistically significant compared to clustering of wild-type CD16-nephrin in the presence of Shp2. The data are mean values and standard errors of the mean.