Figure 7.

PS1 FAD mutations inhibit the EphB2-induced phosphorylation of ephrinB2. A) Mouse fibroblasts derived from PS1-KO mice were cotransduced with ephrinB2 and vector (pMX), WT-PS1, or one of the PS1 mutants, D257A, ΔE9, V82L, A260V, E280A, or G384A. Cells were stimulated with Fc or EphB2-Fc for 10 min, extracted, and immunoprecipitated with anti-ephrinB antibody. IPs were analyzed with anti-phosphotyrosine antibody (top panel) or anti-ephrinB antibody (second panel) by WB. PS1 promotes the EphB2-induced phosphorylation of ephrinB2 on tyrosine. PS1 FAD mutations and catalytically inactive PS1 inhibit it. B) Densitometric quantification of EphB2-induced ephrinB2 phosphorylation on tyrosine. Levels of phospho-ephrinB2 in EphB2-stimulated cells were normalized to phospho-ephrinB2 in Fc-treated cells. Bars represent means ± se of 3 independent experiments.