Regulatory subunit of tax-6/calcineurin A, a calcium-dependent, calmodulin-stimulated protein phosphatase (PubMed:12221132). Confers calcium sensitivity (PubMed:12221132). Plays a role in egg-laying, fertility, growth, movement and cuticle development (PubMed:12221132, PubMed:12684004). Plays a role in sensitivity to CO2 levels (PubMed:18524955). Regulates expression of tax-6 inhibitor rcn-1 (PubMed:12684004). Negatively regulates nicotinic acetylcholine receptor (nAChR) sensitivity to nicotine (PubMed:15990870). Negatively regulates lifespan (PubMed:19279398). Involved in endocytic processes including coelomocyte endocytosis, intestine apical endocytosis and synaptic vesicle recycling (PubMed:20803083, PubMed:21345307). May negatively regulate autophagy (PubMed:19279398). 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) which confers calcium sensitivity. Expressed in sperm, spermatids, spermatheca, male gonads, intestine, nerve cord, hypodermal seam cells, cuticle and excretory canal. Mutants grow slowly and show uncoordinated or lethargic movements (PubMed:12221132, PubMed:12684004). Increased lifespan (PubMed:19279398). Body is small and slender with a transparent appearance resulting from a thinner cuticle (PubMed:12221132, PubMed:12684004). Reduced number of progeny associated with a retention of late stage embryos in the uterus, a reduced sperm count which appears smaller and smoother and with smaller pseudopods (PubMed:12221132, PubMed:12684004). In addition, serotonin-induced egg laying is delayed (PubMed:12221132, PubMed:12684004). Increased susceptibility to nicotine-mediated paralysis (PubMed:15990870). Impaired CO2 avoidance (PubMed:18524955). Increased number of puncta positive for autophagy marker LGG-1 (PubMed:19279398). Impaired coelomocyte endocytosis, intestinal apical endocytosis and recycling of synaptic vesicles at synapses (PubMed:20803083, PubMed:21345307). Belongs to the calcineurin regulatory subunit family.