FIGURE 8.

Basal phosphotyrosine levels of Pyk2 and Pyk2 substrates are elevated in STEP KO mouse brains. A, synaptosomal (P2) fractions from WT and STEP KO littermates were used to determine levels of tyrosine phosphorylation of Pyk2 at Tyr(P)⁴⁰² and total Pyk2 levels. Error bars indicate the SEM of at least three independent experiments (in this and subsequent panels). Quantitative analyses for each were normalized to GAPDH (*, p < 0.05; **, p < 0.01; Student's t test; n = 4). B, phosphorylation of paxillin (Tyr(P)¹¹⁸) and ASAP1 (Tyr(P)⁷⁸²) were determined in P2 fractions with phosphospecific antibodies. Quantitations were normalized to total protein levels, respectively, and then to GAPDH. C, PSD fractions from WT and STEP KO mice were purified. Tyrosine phosphorylation of Pyk2 and ERK1/2 was compared between WT and STEP KO mice (**, p < 0.01; Student's t test; n = 4).