Argos (EGFR Inhibitor)

Argos is a secreted protein that is an inhibitor of the Epidermal Growth Factor Receptor (EGFR) pathway in Drosophila melanogaster. The name derives from the phenotype of mutant flies with eye defects and refers to Argus Panoptes. The mechanism by which Argos attenuates the EGFR pathway is by sequestration of ligand and not by direct interaction with the receptor. Argos binds to the Epidermal growth factor domain of the Drosophila ligand Spitz and prevents its interaction with the Epidermal Growth Factor Receptor. Argos represents the first example of ligand sequestration as a mechanism of inhibition in the ErbB family.