Fig. 4. Biological roles for ROS-generating and Peroxidase-like domains of C. elegans Duox1.

Duox in nematode worms functions in both gastrointestinal immunity and in cuticle stabilization, the latter via tyrosine cross-linking as shown in Fig. 3. Various domains and prosthetic groups are indicated, including the peroxidase-homology domain, which contains a heme group (square with dark center). A point mutation in the peroxidase domain inactivates the cuticle stabilization (producing the blister phenotype), but does not affect GI immunity, indicating that the immunity function does not require a functional peroxidase domain.