Figure 1.

Ptk1 demonstrates ATPase activity and autophosphorylation. (A) Tyrosine kinase assay (Beacon) with the 541-821 C-terminal amino acid fragment of Ptk1 (FPtk1, 5 μg). Positive control and negative kit control were supplied in the assay kit. Negative kinase control is buffer only. Error bars are SD, n = 3. ***P < 0.001 compared to kinase control. (B) Concentration-dependent kinase activity of FPtk1. Negative control is kinase buffer. *P < 0.05; ***P < 0.001 compared to negative control. (C) Autophosphorylation of FPtk1. FPtk1 was dephosphorylated with alkaline phosphatase (AP) followed by treatment with phosphatase inhibitor and ATP or left untreated as a control. Phosphorylated FPtk1 was visualized by Western blotting with phosphotyrosine antibodies.