Required for chromosome segregation and cell division in early embryos (PubMed:31216475). Component of the pid-1 and tost-1 variants of the PETISCO complexes, which have roles in the biogenesis of a class of 21 nucleotide PIWI-interacting RNAs (piRNAs) that possess a uracil residue at the 5'-end (also called 21U-RNAs) and embryogenesis, respectively (PubMed:31147388, PubMed:31216475). Within the tost-1 variant of the PETISCO complex binds to splice leader SL1 RNA fragments to possibly play a role in their processing (PubMed:31147388). Promotes the biogenesis of 21U-RNAs (PubMed:31216475). May form a homodimer (PubMed:31147388). Component of the pid-1 variant of the PETISCO complex (also called the pid-3, erh-2, tofu-6, and ife-3 small RNA complex) containing at least pid-1, tofu-6, ife-3, pid-3, and erh-2, which is required for the biogenesis of a class of 21 nucleotide PIWI-interacting RNAs (piRNAs) that possess a uracil residue at the 5'-end (also called 21U-RNAs) (PubMed:31147388, PubMed:31216475). Within the complex interacts with pid-1 (PubMed:31147388, PubMed:31216475). Component of the tost-1 variant of the PETISCO complex (also called the pid-3, erh-2, tofu-6, and ife-3 small RNA complex) containing at least tost-1, tofu-6, ife-3, pid-3, and erh-2, which plays an essential role in embryogenesis (PubMed:31147388, PubMed:31216475). Within the complex interacts with tost-1 (PubMed:31216475, PubMed:31147388). Within the pid-1 and tost-1 variants of the PETISCO complexes interacts with pid-3 (PubMed:31216475, PubMed:31147388). Within the pid-1 and tost-1 variants of the PETISCO complexes interacts with tofu-6 (via the RRM domain) (PubMed:31216475). In contrast to the pid-1 variant of the PETISCO complex, the tost-1 variant of the PETISCO complex plays a minor role in the biogenesis of 21U-RNAs (PubMed:31147388). Dispersedly distributes throughout the cytoplasm in early embryos (PubMed:31147388). During early embryogenesis, localizes to the nucleus at prophase of cell division, and remains in the cytosol at interphase in 2- and 4-cell embryos (PubMed:31216475). Localizes to puncta in the perinuclear region in the germline syncytium (PubMed:31216475, PubMed:31147388). Expressed in the germline (at protein level). Expressed from early embryogenesis (at protein level) (PubMed:31147388). During early embryogenesis, expressed during prophase and interphase in 2- and 4-cell embryos (PubMed:31216475). RNAi-mediated knockdown results in chromosome segregation and cell division defects in early embryos (PubMed:31216475). RNAi-mediated knockdown results in defective activity of the PIWI-interacting RNA (piRNA) silencing pathway (PubMed:31147388). RNAi-mediated knockdown disrupts the localization of tofu-6 to the perinuclear region of the germline (PubMed:31216475). RNAi-mediated knockdown results in larger tofu-6- and pid-3-expressing foci (PubMed:31216475). RNAi-mediated knockdown results in decreased expression of tost-1 in the germline and in embryos (PubMed:31216475). Belongs to the E(R) family.