Argos is a secreted protein that is an inhibitor of the

epidermal growth factor receptor The epidermal growth factor receptor (EGFR; ErbB-1; HER1 in humans) is a transmembrane protein that is a receptor for members of the epidermal growth factor family (EGF family) of extracellular protein ligands. The epidermal growth factor recept ...

(EGFR) pathway in ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Ch ...

''. Argos inhibits the EGFR pathway by sequestering the EGFR ligand

Spitz Spitz (derived from the German word ''spitz'' 'pointed') is a type of domestic dog characterized by long, thick, and often white fur, and pointed ears and muzzles. The tail often curls over the dog's back or droops. While all of the breeds rese ...

. Argos binds the

epidermal growth factor Epidermal growth factor (EGF) is a protein that stimulates cell growth and differentiation by binding to its receptor, EGFR. Human EGF is 6-k Da and has 53 amino acid residues and three intramolecular disulfide bonds. EGF was originally descr ...

domain of Spitz, preventing interaction between Spitz and EGFR. Argos does not directly interact with EGFR. Argos represents the first example of ligand sequestration as a mechanism of inhibition in the

ErbB The ErbB family of proteins contains four receptor tyrosine kinases, structurally related to the epidermal growth factor receptor (EGFR), its first discovered member. In humans, the family includes Her1 (EGFR, ErbB1), Her2 (Neu, ErbB2), Her3 (Er ...

(EGFR) family.

Function

Argos is secreted from cells in ''D. melanogaster''. Outside the cell, it binds the EGFR-activator Spitz, preventing it from binding and activating EGFR. ''Drosophila'' with mutations that inactivate Argos have deformed eyes with extra photoreceptors and a small optic lobe due to disruption of EGFR's role in eye development. The name of the gene derives from the phenotype of mutant flies with eye defects and refers to

Argus Panoptes Argus or Argos Panoptes ( grc, Ἄργος Πανόπτης, All-seeing Argos) is a many-eyed giant in Greek mythology. Mythology Argus Panoptes (), guardian of the heifer-nymph Io and son of Arestor and probably Mycene (in other version so ...

Structure

Crystallographic studies have revealed that Argos does not contain an EGF domain as originally expected. Rather, Argos is composed of 3 separate domains that have homology to one another, termed the Argos domain. The Argos domain has features in common with the three finger toxin fold that is found in a number of proteins including

TGF beta receptor Transforming growth factor beta (TGFβ) receptors are bitopic protein, single pass Receptor protein serine/threonine kinase, serine/threonine kinase receptors that belong to TGFβ superfamily receptor, TGFβ receptor family. They exist in sever ...

s and the urokinase (uPA) receptor.

References

Proteins Drosophila melanogaster genes {{protein-stub

Function

Structure

See also

References