Receptor Tyrosine Kinases Take a Direct Route to Mitochondria: An Overview

Receptor tyrosine kinases (RTKs) are cell surface receptors that transmit extracellular signals to the interior of the cell activating multiple signaling cascades: the binding of specific extracellular ligands activates RTKs which act as a scaffold at plasma membrane level for the recruitment and activation of several signaling molecules. A paradigm shift emerged when an alternative direct signaling pathway was discovered: RTKs may move from cell surface to nucleus where they transduce the signals in a direct way. More recently, evidence has accumulated that RTKs may also translocate to mitochondria and regulate their functions, i.e., by altering tyrosine phosphorylation of specific mitochondrial proteins. This latter emerging pathway is here reviewed and discussed.