Protein tyrosine kinase, Pyk2 (CAKb, RAFTK, CADTK), is a nonreceptor tyrosine kinase structurally related to focal adhesion kinase (FAK). Pyk2 is predominantly expressed in cells derived from hematopoietic lineages and in the central nervous system. Pyk2 is one of the signaling mediators for the G-protein-coupled receptors and MAP kinase signaling pathway. It plays an important role in cell spreading and migration of various cell types. In T-cells, Pyk2 is tyrosine phosphorylated and activated upon ligation of TCR. Phosphorylation of Tyr-402 is required for the phosphorylation of other tyrosines in Pyk2 and provides a binding site for Fyn SH2 during T-cell activation.
