Guanyl-specific endoribonuclease which cleaves the phosphodiester bond in single-stranded RNA between the 3'-guanylic residue and the 5'-OH residue of adjacent nucleotide, resulting in the formation of a corresponding 2',3'-cyclic phosphate intermediate (PubMed:26787882). Essential role in male and female postembryonic germline development; maternally provided protein maintains a population of proliferating germ cells and zygotic expression is required for correct oogenesis (By similarity). Together with the P-granule component pgl-3, is involved in the formation of P-granules (By similarity). Together with pgl-3, probably recruits other granule components such as pos-1, mex-3 and glh-1 to P-granules (By similarity). In addition, may act redundantly with pgl-3 to protect germ cells from excessive germline apoptosis during normal oogenesis and development of the two gonadal arms (By similarity). This may in part be through regulating the localization of sir-2.1 which is involved in germ cell apoptosis (By similarity). May protect somatic cells from excessive apoptosis during normal development (By similarity). [RNA] containing guanosine + H2O = an [RNA fragment]-3'-guanosine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA fragment]. Does not require metal ions for catalytic activity. Homodimer (PubMed:26787882). Interacts with pgl-2 and pgl-3; this association is not required for P-granule localization of either pgl-2 or pgl-3 (By similarity). Interacts with ife-1 (By similarity). Interacts with prmt-1; the interaction is direct (By similarity). Interacts with nmad-1 (By similarity). Interacts with P granule components meg-1, meg-3 and meg-4 (By similarity). Localizes to P granules in germline precursor cells. Localizes to P granules in germ cells at all stages of development except in spermatogenesis. Co-localizes with pgl-3 in P-granules, but localization in P-granules is not dependent on an association with pgl-3. The dimerization domain also acts as a hinge; changes in its structure probably impact oligomerization and RNA-binding. The RNA-binding RGG-box is required for the recruitment of some P-granule components such as pos-1 and probably mRNA, but is dispensable for granule formation.