Modular peptide recognition domains in eukaryotic signaling.

A characteristic feature of cellular signal transduction pathways in eukaryotes is the separation of catalysis from target recognition. Several modular domains that recognize short peptide sequences and target signaling proteins to these sequences have been identified. The structural bases of the specificities of recognition by SH2, SH3, and PTB domains have been elucidated by X-ray crystallography and NMR, and these results are reviewed here. In addition, the mechanism of cooperative interactions between these domains is discussed.