Calcium-dependent, calmodulin-stimulated protein phosphatase (PubMed:12221132, PubMed:16481400, PubMed:22300764, PubMed:23805378). Dephosphorylates arrd-17 (PubMed:22300764). Dephosphorylates daf-16 at 'Ser-319' which regulates daf-16 nuclear translocation (PubMed:23805378). Dephosphorylates calcium permeable cation channel pkd-2 at 'Ser-534' (PubMed:16481400). Regulates male mating behavior including response to hermaphrodite contact and vulva location and localization of pkd-2 to neuronal cilium (PubMed:16481400). Negatively regulates several sensory behaviors including thermotaxis in ADF neurons, osmosensation in ASH neurons, olfaction adaptation in AWC neurons and sensitivity to CO2 levels (PubMed:18524955, PubMed:11879652). Plays a role in modulating temperature-dependent calcium responses in AFD neurons and together with tax-6 inhibitor rcan-1 regulates thermotaxis in AFD neurons (PubMed:26232604). Regulates expression of rcan-1 (PubMed:12684004). In response to changes in intracellular calcium levels may also regulate nuclear translocation of transcriptional regulators such as crtc-1 (PubMed:26232604). Plays a role in egg-laying, body-size, fertility, growth, movement and cuticle development (PubMed:12684004, PubMed:15522306, PubMed:17113567, PubMed:22300764, PubMed:27871170). Negatively regulates lifespan (PubMed:19279398). Promotes transcription activator crtc-1 nuclear localization, probably by dephosphorylating crtc-1 and thereby negatively regulates lifespan (PubMed:21331044). Regulates expression of chemoreceptor srt-2 in AWC neurons probably downstream of Ser/Thr kinase kin-29 (PubMed:17113567). Negatively regulates nicotinic acetylcholine receptor (nAChR) sensitivity to nicotine (PubMed:15990870). Plays a role in several endocytic processes including in coelomocyte endocytosis, intestine apical endocytosis and synaptic vesicle recycling (PubMed:20803083, PubMed:21345307). May negatively regulate excitatory GABA receptor exp-1 during enteric muscle contraction (PubMed:16084527). May negatively regulate autophagy (PubMed:19279398). H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 1 Fe(3+) ion per subunit. Binds 1 zinc ion per subunit. Activated by Ca(2+)-bound calmodulin following an increase in intracellular Ca(2+) (By similarity). At low Ca(2+) concentrations, the catalytic subunit (also known as calcineurin A) is inactive and is bound to the regulatory subunit (also known as calcineurin B) in which only two high-affinity binding sites are occupied by Ca(2+) (PubMed:12221132). In response to elevated calcium levels, the occupancy of the low-affinity sites on calcineurin B by Ca(2+) causes a conformational change of the C-terminal regulatory domain of calcineurin A, resulting in the exposure of the calmodulin-binding domain and in the partial activation of calcineurin A (PubMed:12221132). The subsequent binding of Ca(2+)-bound calmodulin leads to the displacement of the autoinhibitory domain from the active site and possibly of the autoinhibitory segment from the substrate binding site which fully activates calcineurin A (By similarity). Inhibited by immunosuppressant cyclosporin A (CsA) (PubMed:12221132). Forms a complex composed of a calmodulin-dependent catalytic subunit tax-6 (also known as calcineurin A) and a regulatory Ca(2+)-binding subunit cnb-1 (also known as calcineurin B) (PubMed:12221132). In response to an increase in Ca(2+) intracellular levels, forms a complex composed of tax-6, cnb-1 and cmd-1/calmodulin (By similarity). Interacts with cmd-1/calmodulin in a Ca(2+)-dependent manner (PubMed:17854888). Interacts (via catalytic domain) with rcan-1; the interaction is calcium-dependent and inhibits tax-6 catalytic activity (PubMed:12684004, PubMed:26232604). Interacts with exp-1; the interaction is calcium and cnb-1-independent (PubMed:16084527). Interacts with arrd-17 (PubMed:22300764). Interacts with kin-29 (PubMed:17113567). Interacts with cnp-2 (PubMed:18593529). Interacts with daf-16 (PubMed:23805378). Interacts with dyn-1 (PubMed:20803083). Expressed in head and tail neurons, ventral nerve cord, body wall and vulva muscles, sperm and spermatheca (PubMed:12221132). Expressed in hypodermal seam cells (PubMed:15522306). Expressed in intestinal and anal depressor muscles (PubMed:16084527). In male, expressed in CEM, HOB and ray RnB neurons (PubMed:16481400). Isoform a: Expressed in thermosensory ADF neurons, chemosensory ASE, AWA and AWC neurons, osmosensory ASH neurons and AIY and AIZ interneurons (PubMed:11879652). Expressed in body wall, vulva and pharyngeal muscles (PubMed:11879652). Expressed in embryos and at all larval stages. The autoinhibitory domain prevents access to the catalytic site. The autoinhibitory segment prevents access to the substrate binding site. Possible isomerization of Pro-334 within the SAPNY motif triggers a conformation switch which affects the organization and thus accessibility of the active site and the substrate binding region (PxIxIF motif). The trans- to cis-transition may favor calcineurin A activation and substrate binding. The reverse cis- to trans-transition may be enhanced by peptidyl-prolyl isomerases such as PPIA. Shorter body length and reduced serotinin-induced egg laying as compared to wild-type (PubMed:27871170). Reduced calcium responses in AFD neurons upon a temperature increase from 16 to 20 degrees Celsius as compared to wild-type. At 17 degrees Celsius displays thermophilic behavior, preferentially migrating towards hotter regions (PubMed:26232604). RNAi-mediated knockdown results in an increase in lifespan (PubMed:21331044, PubMed:23805378). Also causes nuclear exclusion of crtc-1 (PubMed:21331044). Belongs to the PPP phosphatase family. PP-2B subfamily.