Plays a role in cuticle biogenesis (PubMed:15454573, PubMed:23028364, PubMed:25480962). In complex with doxa-1 and the dual oxidase bli-3, promotes the generation of reactive oxygen species (ROS) and tyrosine cross-linking of collagen, thus stabilizing cuticular extracellular matrix (PubMed:23028364). Interacts with doxa-1 and bli-3. Expressed in the body wall (hyp7 hypodermal syncitium), pharynx and vulva. Expressed in a punctate pattern along the thick region of the hypodermis. Expressed in cells along the anteroposterior axis from the 1.5-fold stage of embryogenesis until the 3-fold stage when expression decreases but increases in the body surface with prominent expression in the lateral hypodermal cells (PubMed:23028364, PubMed:15454573). Expressed in the pharynx and body wall from the larval stage to adulthood. Embryonic lethal (PubMed:23028364). Mutants display dumpy and blistered cuticle phenotypes (PubMed:23028364). Blisters contain unidentified cellular material (PubMed:23028364, PubMed:25480962). Resistant to iodide toxicity (PubMed:25480962). RNAi-mediated knockdown results in the lethality of more than 95% of progeny at the larval stage (PubMed:15454573). Most larval arrest occurs at the L4 larval stage and is characterized by body swelling and abnormal epidermal morphology, which includes blistering of the cuticle (PubMed:15454573, PubMed:25480962). The few animals that develop into adults have a distended body shape and/or epidermal blistering (PubMed:15454573). Abnormal cuticular and hypodermal morphology including splits in the cortical layer of the cuticle, abnormal gaps between the hypodermis and musculature and inconsistent thickness of the hypodermis (PubMed:15454573, PubMed:25480962). Impaired hypodermal membrane integrity and reduced fibrous organelles (PubMed:15454573). Belongs to the tetraspanin (TM4SF) family.