Paul Dent (Department of Medicine, University of Virginia Health Sciences Center, Charlottesville): "Investigators in signal transduction want to understand in detail the molecular steps by which growth factors, hormones, and oncogenes regulate cell function. Much of this control is via protein phosphorylation. MAP kinase is activated by dual phosphorylation at tyrosine and threonine residues, occurring in a TEY motif, catalyzed by a protein- tyrosine/threonine kinase termed MAP kinase kinase, or MEK (MAP kinase/ERK kinase). MAP kinase kinase (MKK) is remarkably specific for MAP kinase as the protein substrate and is itself regulated by serine/threonine phosphorylation.
"At the time we initiated these studies, the activating kinase for MKK had not been identified. Several clues suggested that it was worthwhile to test the ability of v- Raf to phosphorylate and activate MKK. Similar stimuli activate Raf and MAP kinase, and both appeared to function downstream from p21 Ras, inferred from studies by ...
