Probable phosphatase which plays a redundant role with gsp-4 in spermatogenesis by regulating sister chromatid segregation during meiosis (PubMed:16943775, PubMed:22042574). In addition, involved in sperm motility by controlling the dynamic disassembly of major sperm proteins (MSP) in the spermatozoan pseudopodium (PubMed:22042574). H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Co-localizes with MSP in oblong stripes in the cytoplasm of inactive sperm and in the pseudopodium in activated sperm. Expressed in male germline including spermatocytes, spermatids and spermatozoa. Expressed at all stages of spermatocyte meiosis. No obvious phenotype (PubMed:22042574). Simultaneous RNAi-mediated knockdown of gsp-3 and gsp-4 results in male sterility due to chromosome segregation defects during sperm meiosis (PubMed:16943775). gsp-3 and gsp-4 double mutant hermaphrodites have egg laying defects and no viable progeny. gsp-3, gsp-4 and him-8 triple mutants have incomplete separation of sister chromatids during the second meiotic segregation. Mislocalization of MSP in activated sperm. In addition, have partial reduction in mpk-1 phosphorylation and air-2 association with bivalent chromosomes in the most proximal oocyte in response to MSP (PubMed:22042574). Belongs to the PPP phosphatase family. Due to the high similarity between gsp-3 and gsp-4, the antibody used to study expression does not distinguish between the two proteins.