Fig. 8: A c-terminal palindromic phospho-motif controls c-Src function.
a Cartoon representation of the kinase-substrate (chain A and B) asymmetric engagement of two c-Src molecules in the crystal structure. Left panel, close in view of the c-terminal aa sequence of c-Src containing the palindromic PQYQP motif at the interface between the two molecules showing residues coordinated by intra- and intermolecular interactions. b Schematic diagram of the functional domains and main autophosphorylation sites of c-Src. Different c-terminal sequence variants are depicted. WB of samples from a time-course autophosphorylation experiment with c-Src WT, v-Src and 531X (3D-construct, 1 μM) in the presence of ATP (1 mM) and MgCl2 (2 mM) for 0–60 min using the indicated antibodies. The total amount of protein was visualized by Coomassie staining. c Enzyme kinetics and catalytic efficiency constant (kcat/KM, fold-change) for ATP using Src WT, v-Src and 531X (3D-construct, 1 μM final concentration) at a fixed concentration (2–4 mg/ml) of Abl peptide. Data represent the mean ± SEM of 3 experiments in duplicate (n = 6). d WB of samples from a time-course phosphorylation experiment with c-Src WT, v-Src and 531X (3D-construct, 1 μM) in the presence of a c-Src KD K298M (3 μM) for 0–60 min using the indicated antibodies. The total amount of protein was visualized by Coomassie staining. Data are representative of 3 independent experiments. e WB of samples from a time-course phosphorylation experiment with c-Src KD WT (1 μM), in the presence of substrate surrogates c-Src, v-Src and 531X K298M (3D-construct, 3 μM) for 0–60 min using the indicated antibodies. The total amount of protein was visualized by Coomassie staining. Phospho-tyrosine 530 signal quantification on the active kinase molecule, data represent mean ± SEM of 3 experiments (n = 3), ** p = 0.003, **** p = 0.0001, 2-way ANOVA multiple comparison test. Source data are provided in the Source Data file.
