Dephosphorylates auto-phosphorylated Ca(2+)/calmodulin-dependent protein kinase unc-43/CAMKII in vitro (PubMed:11559703, PubMed:23760267). Involved in the regulation of sex determination (PubMed:8824590). Together with fem-3, required for male sexual development by promoting the proteasomal-mediated degradation of tra-1, a transcription repressor of male-specific genes (PubMed:17609115). Promotes apoptosis (PubMed:11559703). H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 2 magnesium or manganese ions per subunit. Component of a complex containing fem-1, fem-2 and fem-3 (PubMed:23760267). Interacts (via N-terminus) with fem-1 and fem-3 (PubMed:17609115, PubMed:23760267, PubMed:8824590). Component of the CBC(fem-1) E3 ubiquitin-protein ligase complex, at least composed of cul-2, elc-1, tra-1, fem-1, fem-2 and fem-3; mediates the ubiquitination and subsequent proteasomal degradation of tra-1 (PubMed:17609115). Interacts with tra-1 (PubMed:17609115). Interacts with sel-10 (PubMed:15306688). Belongs to the PP2C family.