UC Berkeley

The Epidermal Growth Factor Receptor (EGFR), also known as ErbB1 or HER1 in humans, is a member of the ErbB family. EGFR is a receptor tyrosine kinase (RTK) responsible for communicating cellular signaling across the plasma membrane related to cell proliferation, metabolism, and migration. EGFR mutations and overexpression are known to be related to cancer. Thus, understanding EGFR biology and the molecular mechanism of EGFR activation can lead to important therapeutic strategies. The importance of the juxtamembrane (JM) domain of the EGFR has gathered attention as evidence showed that its intermolecular and intramolecular interactions are crucial for EGFR function.In this dissertation, I describe my graduate work in four chapters detailing the study of the EGFR JM function and its role in regulating the downstream biology of the EGFR. Chapter 1: This chapter builds on the literature review and previous efforts, introducing the role and importance of EGFR in cellular biology, and the role of the JM domain in EGFRactivation. In this chapter, JM structure and the manipulation to affect EGFR signaling were described. Chapter 2: This chapter describes peptides mimicking the JM domain dimer in activated EGFR used for high-resolution structural studies. The designs of these JM-mimicking peptides were detailed. Peptide synthesis, purification, and characterizations that reveal the secondary structure were discussed. Chapter 3: Looking beyond the JM domain, the structural study described in this chapter focused on peptides containing both the transmembrane domain (TM) and the JM domain segment to investigate the allosteric relationship within EGFR. Preparation and characterization of membrane mimics that stabilize TM-containing peptides were reported. Chapter 4: In the final chapter, I report a collaborative work I partake that reveals the effect of JM structure and conformation on EGFR biology in terms of cellular trafficking and receptor degradation. Another preliminary work using APEX2-based proximity labeling toward mass spectrometry proteomics was reported. Finally, this chapter summarized the outlook on future directions following the groundwork laid out in the scope of this dissertation.