The Homodimerization Propensities of Transmembrane Helices Selected from a Combinatorial Library Characterized using In Vivo Phosphorylation and Dimerization Assays

Abstract

Receptor tyrosine kinases (RTKs) play vital roles in cell proliferation, differentiation, survival and migration; however, the mechanisms of RTK dimerization and activation are not well understood. To gain insight into the role of RTK transmembrane (TM) domains in the dimerization process, and to determine which amino acids are important for the dimerization of Neu, a member of the epidermal growth factor receptors (EGFRs) expressed in rats, a peptide library was generated via combinatorial chemistry based on the sequence of the Neu TM domain. Three sequences that have a strong tendency to form dimers and two monomeric sequences were identified by SDS-PAGE-based high throughput screening. In order to evaluate their dimerization propensities in cells, we have substituted the Neu TM domain with these sequences, and we are studying the effect of these substitutions on Neu dimerization and activity. This work will not only enable us to understand the determinants of RTK dimerization, but also will be useful for identifying inhibitory peptide sequences from large peptide libraries.