An electrostatic engine model for autoinhibition and activation of the epidermal growth factor receptor (EGFR/ErbB) family.
We propose a new mechanism to explain autoinhibition of the epidermal growth factor receptor (EGFR/ErbB) family of receptor tyrosine kinases based on a structural model that postulates both their juxtamembrane and protein tyrosine kinase domains bind electrostatically to acidic lipids in the plasma membrane, restricting access of the kinase domain to substrate tyrosines. Ligand-induced dimerization promotes partial trans autophosphorylation of ErbB1, leading to a rapid rise in intracellular [Ca(2+)] that can activate calmodulin. We postulate the Ca(2+)/calmodulin complex binds rapidly to residues 645--660 of the juxtamembrane domain, reversing its net charge from +8 to -8 and repelling it from the negatively charged inner leaflet of the membrane. The repulsion has two consequences: it releases electrostatically sequestered phosphatidylinositol 4,5-bisphosphate (PIP(2)), and it disengages the kinase domain from the membrane, allowing it to become fully active and phosphorylate an adjacent ErbB molecule or other substrate. We tested various aspects of the model by measuring ErbB juxtamembrane peptide binding to phospholipid vesicles using both a centrifugation assay and fluorescence correlation spectroscopy; analyzing the kinetics of interactions between ErbB peptides, membranes, and Ca(2+)/calmodulin using fluorescence stop flow; assessing ErbB1 activation in Cos1 cells; measuring fluorescence resonance energy transfer between ErbB peptides and PIP(2); and making theoretical electrostatic calculations on atomic models of membranes and ErbB juxtamembrane and kinase domains.
McLaughlin
Stuart
S
Department of Physiology and Biophysics, HSC, Stony Brook University, Stony Brook, NY 11794, USA. Stuart.McLaughlin@StonyBrook.edu
Smith
Steven O
SO
Hayman
Michael J
MJ
Murray
Diana
D
D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002522:Chlorocebus aethiops; D003198:Computer Simulation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism; D066246:ErbB Receptors / Q000737:chemistry* / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry*; D008954:Models, Biological; D008956:Models, Chemical; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity
D004791:Enzyme Inhibitors; D008051:Lipid Bilayers; D020409:Molecular Motor Proteins; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases