Speakers
Co-Director, Cancer Biology Institute
Details
The 58 growth factor receptor tyrosine kinases (RTKs) provide a useful palette of signaling mechanisms used in biology by receptors with a single transmembrane domain. Although initial studies of examples such as the epidermal growth factor receptor (EGFR) suggested a simple ligand-induced dimerization mechanism, it is now clear that these receptors are much more complex than this, with substantial diversity across the superfamily. Our studies of human EGFR activation by different activating ligands, combined with studies of invertebrate EGFRs, suggest a much more complicated picture for EGFR regulation. Early work with the Drosophila and C. elegans EGFRs suggested models for allosteric regulation of dimeric EGF receptors. More recently, we determined crystal structures of the human EGFR extracellular region bound to different activating ligands, revealing distinct structures with important implications for fine control of EGFR activation. Further investigation has revealed that certain EGFR ligands function as partial or biased agonists of the receptor, likely through a kinetic proofreading mechanism. I will also summarize recent progress with another important group of RTK families in which the intracellular domains contain pseudokinases – namely the Ryk, Ror, and CCK4/PTK7 families. These RTKs are all thought to be regulated by extracellular binding of Wnt ligands, but differ importantly from other Wnt receptors and must signal in unique ways.