scholarly journals An Electrostatic Engine Model for Autoinhibition and Activation of the Epidermal Growth Factor Receptor (EGFR/ErbB) Family

2005 ◽  
Vol 126 (1) ◽  
pp. 41-53 ◽  
Author(s):  
Stuart McLaughlin ◽  
Steven O. Smith ◽  
Michael J. Hayman ◽  
Diana Murray

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 [Ca2+] that can activate calmodulin. We postulate the Ca2+/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 (PIP2), 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 Ca2+/calmodulin using fluorescence stop flow; assessing ErbB1 activation in Cos1 cells; measuring fluorescence resonance energy transfer between ErbB peptides and PIP2; and making theoretical electrostatic calculations on atomic models of membranes and ErbB juxtamembrane and kinase domains.

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Yongjian Huang ◽  
Shashank Bharill ◽  
Deepti Karandur ◽  
Sean M Peterson ◽  
Morgan Marita ◽  
...  

The epidermal growth factor receptor (EGFR) is activated by dimerization, but activation also generates higher-order multimers, whose nature and function are poorly understood. We have characterized ligand-induced dimerization and multimerization of EGFR using single-molecule analysis, and show that multimerization can be blocked by mutations in a specific region of Domain IV of the extracellular module. These mutations reduce autophosphorylation of the C-terminal tail of EGFR and attenuate phosphorylation of phosphatidyl inositol 3-kinase, which is recruited by EGFR. The catalytic activity of EGFR is switched on through allosteric activation of one kinase domain by another, and we show that if this is restricted to dimers, then sites in the tail that are proximal to the kinase domain are phosphorylated in only one subunit. We propose a structural model for EGFR multimerization through self-association of ligand-bound dimers, in which the majority of kinase domains are activated cooperatively, thereby boosting tail phosphorylation.


1986 ◽  
Vol 6 (4) ◽  
pp. 1329-1333
Author(s):  
R C Schatzman ◽  
G I Evan ◽  
M L Privalsky ◽  
J M Bishop

The retroviral oncogene v-erb-B encodes a truncated version of the receptor for epidermal growth factor. To define the disposition of the v-erb-B protein within cells and across the plasma membrane, we raised antibodies against defined epitopes in the protein and used these in immunofluorescence to analyze cells transformed by v-erb-B. A small fraction of the v-erb-B protein was found on the plasma membrane in a clustered configuration. The bulk of the protein was located in the endoplasmic reticulum and Golgi apparatus. Epitopes near the amino terminus of the v-erb-B protein were displayed on the surface of the cell, whereas epitopes in the protein kinase domain were located exclusively within cells. We conclude that the v-erb-B protein spans the plasma membrane in a manner similar or identical to that of the epidermal growth factor receptor, even though the viral transforming protein does not possess the signal peptide that is thought to direct insertion of the receptor into the membrane.


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