Intracellular signalling mediated by protein-tyrosine kinases: networking through phospholipid metabolism

In recent years, it has become apparent that receptor-mediated intracellular signals are not linear cascades beginning at the plasma membrane and terminating with the production of a needed metabolite or the induction of gene expression. Instead, complex networks of interactive intracellular signals are activated in response to extracellular stimuli. Many responses to extracellular stimuli are mediated by protein-tyrosine kinases (PTKs). Activating PTKs leads to the recruitment of a variety of intracellular signalling molecules that execute a complex set of instructions. The response to PTK activity is dependent upon which PTK is activated and the cellular context in which the PTK exists. Several signalling molecules recruited by PTKs are involved in the metabolism of phospholipids. In this Mini Review, intracellular signalling networks activated by PTKs are discussed with an emphasis on the potential for generating highly specific and sophisticated responses to PTK activity through phospholipid metabolism.