# The immunoglobulin domain of C. elegans IGEG-2/EGF is required for its function

## TL;DR

The study shows that the immunoglobulin domain of a protein in C. elegans is crucial for its signaling function related to EGF receptors.

## Contribution

The research identifies the essential role of the IgD domain in IGEG-2/EGF signaling in C. elegans.

## Key findings

- The IgD domain of IGEG-2 is essential for its signaling function.
- Widespread expression of IGEG-2 leads to EGFR hyperactivation phenotypes.
- The mechanism behind the IgD domain's necessity remains unknown.

## Abstract

Epidermal Growth Factor (EGF) family ligands mediate signaling events in development and physiology across species. These ligands are transmembrane proteins that undergo ectodomain shedding to release the soluble EGF domain, which mediates interaction with EGF receptors (EGFR). Some EGF ligand ectodomains also contain an immunoglobulin-like domain (IgD), and the function of this domain within Ig-EGFs varies.

C. elegans

IGEG-2
is an EGFR ligand of unknown function, identified and named for its Ig and EGF domains. The EGF domain appears to be functional, as widespread expression of
IGEG-2
produces phenotypes associated with EGFR hyperactivation. Here we use these phenotypes to investigate the contribution of the
IGEG-2
IgD, and we find it to be essential for
IGEG-2
/EGF signaling. The mechanism underlying this strict IgD dependence is not known.