Fig. 1.

Doublecortin binds directly to a synthetic peptide bearing the phospho-FIGQY motif, and mutations in doublecortin that cause X-linked lissencephaly abolish the doublecortin-phospho-FIGQY motif interaction. A, Coomassie blue-stained gel of purified monodisperse recombinant doublecortin (2 μg).B, Results of a representative peptide-binding assay. The y-axis of the graph represents the doublecortin binding to the synthetic peptides in arbitrary units (A.U.) and was obtained as described in Materials and Methods.C, Coomassie blue-stained gel of partially purified recombinant doublecortin and doublecortin mutants: R59H, D62N, and G253D. D, Results of a representative peptide-binding assay. The y-axis of the graph represents in arbitrary units the doublecortin binding to the synthetic peptides. Black bars represent binding for wild-type doublecortin, white bars represent binding for R59H doublecortin, diagonally striped bars represent binding for D62N doublecortin, andhorizontally striped bars represent binding for G253D doublecortin. In B and D, the peptides used are listed below each bar representing doublecortin binding, phospho–FIGQY, FIGQY, FIGQF, or no peptide.