Molecular Architecture of a Network of Potential Intracellular EGFR Modulators: ARNO, CaM, Phospholipids, and the Juxtamembrane Segment

Epidermal growth factor receptors (EGFRs) are central cellular signaling interfaces whose misregulation is related to several severe diseases. Although ligand binding to the extracellular domain is the most obvious regulatory element, also intracellular factors can act as modulators of EGFR activity. The juxtamembrane (JM) segment seems to be the receptor's key interaction interface of these cytoplasmic factors. However, only a limited number of cytoplasmic EGFR modulators are known and a comprehensive understanding of their mode of action is lacking. Here, we report ARNO, a member of the cytohesin family, as another JM-binding protein and structurally characterize the ARNO-EGFR interaction interface. We reveal that its binding mode displays common features and distinct differences with JM's interaction with calmodulin and anionic phospholipids. Furthermore, we show that each interaction can be modulated by additional factors, generating a distinctly regulated network of possible EGFR modulators acting on the intracellular domain of the receptor. [Display omitted] •EGFR's juxtamembrane segment can act as hub for potential intracellular modulators•The competitive network comprises CaM, lipids, ARNO, and individual (co)factors•High-resolution insights into interaction region of EGFR and ARNO from both sides•ARNO shares a common EGFR-binding site with calmodulin Interactions with the intracellular juxtamembrane (JM) segment of the membrane spanning epidermal growth factor receptor (EGFR) can modulate its vital signaling. Viegas et al. unravel an interaction network comprising lipids, proteins, as well as individual cofactors, and characterize the molecular mechanisms of the respective interactions with EGFR's JM segment.