Molecular Dynamics Simulations of the Association of Model Transmembrane Domains of Epidermal Growth Factor Receptors

Epidermal growth factor receptors have a major impact in cellular signal transduction. Dimerization/oligomerization of ErbB's has been attributed to ligand binding to the extracellular protein domain. Recent experimental studies suggest that protein transmembrane domains promote dimerization. Interactions between amino acids similar to proposed motifs in the well-studied dimer of Glycophorin-A, could favor the close packing of helix interfaces. We performed detailed atomistic simulations of individual ErbB transmembrane domains in a lipid bilayer and compared to the Glycophorin-A helical transmembrane domain. Using the structure from the single atomistic domains, we parameterized efficient coarse grain models to study the dimerization process. Molecular dynamics simulations, longer than a microsecond, suggest that all transmembrane domains of Glycophorin, ErbB-1, ErbB-2, ErbB-3 and ErbB-4 associate in well defined conformations directed by specific interactions. Our simulations support experimental evidence that transmembrane domains contribute significantly to the dimerization process.