Probably a receptor-regulated SMAD (R-SMAD) that is an intracellular signal transducer and transcriptional modulator activated by TGF-beta-like daf-7 signaling (PubMed:10625546, PubMed:20081192). Plays a role in TGF-beta-like daf-7 signaling in regulating entry into a developmentally arrested larval state known as dauer, in response to harsh environmental conditions; partially redundant with R-SMAD daf-14 (PubMed:10625546, PubMed:20081192). Plays a role in inhibiting mitosis and promoting a switch to meiosis in the germ line, perhaps by down-regulating lag-2 transcription in the gonadal distal tip cells (DTCs) (PubMed:20081192). In cooperation with orphan nuclear receptor nhr-69 modulates the Insulin/IGF-1-like signaling (IIS) pathway, perhaps by regulating expression of the potassium channel exp-2, which in turn modulates the secretion of the insulin-like peptide daf-28 (PubMed:22359515). Homodimer (Probable). Interacts with R-SMAD daf-14 and co-SMAD daf-3 (PubMed:20081192). Interacts with orphan nuclear receptor nhr-69 (PubMed:22359515). Localizes to the nucleus in a TGF-beta-like receptor daf-1 dependent manner. Expressed in the excretory cell and gonadal distal tip cells (DTCs). Expressed in developing embryos from the pre-comma stage through to hatching (PubMed:20081192). Most highly expressed in larval stage L1 and gradually decreases into adulthood (PubMed:20081192). In larval stages, expressed throughout development in the ventral nerve cord, intestine, gonadal distal tip cells (DTCs) and subsets of head and tail neurons, most strongly in head neurons ASI and ADL (PubMed:20081192). Belongs to the dwarfin/SMAD family.