Analyses of Kek1 binding to the EGFR

Abstract

The Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase, whose activation controls cell proliferation, survival, migration, and cell fate determination. As such, activating mutations to EGFR is associated with many cancers, including those of the breast, brain, and lung. Therapeutic approaches typically involve molecules designed to inhibit the receptor (Wieduwilt et al., 2008). Kekkon1 is an inhibitor of Drosophila EGFR (dEGFR) and is one of a family (Kek) of six transmembrane molecules in Drosophila. Interestingly, within the family only Kek1 inhibits the Drosophila receptor and the extracellular and transmembrane regions have been identified as the domains required for inhibition. The extracellular region consists of N-insert, seven LRRs, flanked by cysteine rich domains and an Ig domain. While the importance of the LRRs to Kek1’s ability to bind the receptor have been established, key questions remain. Are the cysteine rich flanking regions involved in binding, what LRR residues within the predicted binding pocket drive specificity of the interaction, and is the N-insert required for inhibition in vivo? To investigate these, I: undertook a combined phylogenetic and biochemical analyses of Kek1 orthologs, generated a Kek1 variant lacking the N-insert, Kek1∆N, for in vivo functional tests, and used in silico modeling to examine the predicted binding pocket. By better defining the key sequence features of the binding pocket, I hope to solve the binding pocket puzzle. This critical insight to the inhibitory mechanism of Kek1 could then provide the basis for future cancer therapeutics