Protein phosphatase which plays an essential role in meiosis and in early embryonic mitosis. During spermatocyte meiosis and the first embryonic mitosis, regulates centrosome maturation, and thus spindle formation, by recruiting some of the components of the pericentriolar material (PCM). During oocyte meiosis I, regulates meiotic chromosome dynamics including synapsis-independent chromosome pairing, restriction of synapsis to homologous chromosomes, programmed DNA double-strand break initiation and crossover formation resulting in chiasma formation. During oocyte meiosis II and probably together with regulatory subunit ppfr-1, may regulate microtubule severing by dephosphorylating and activating mei-1, a component of the katanin microtubule severing complex. H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 2 manganese ions per subunit. Serine/threonine-protein phosphatase 4 (PP4) occurs in different assemblies of the catalytic and one or more regulatory subunits. The regulatory subunits are likely to be ppfr-1, ppfr-2, ppfr-4 and smk-1. Interacts with mei-1. Localizes at centrosomes from prophase to telophase but not during interphase. Also localizes to the cytoplasm throughout the cell cycle. Methylation at the C-terminal Leu-333 is critical for interactions with regulatory subunits. Belongs to the PPP phosphatase family. PP-4 (PP-X) subfamily.