Functions as a calcium permeable cation channel (PubMed:15862350). Required for 2 aspects of male mating behavior: response to hermaphrodite contact and vulva location (PubMed:11553327, PubMed:12411744, PubMed:15862350, PubMed:15753033, PubMed:18037411, PubMed:28745435). Acts in the same pathway as lov-1 and atp-2 in response behavior (PubMed:11553327). Synthesized in the endoplasmic reticulum, and then packaged into vesicles that are transported to the ciliary base and inserted into the ciliary membrane. Localizes to both the ciliary base and cilium proper. Exclusively expressed in a subset of 3 categories of adult male sensory neurons: ray neurons, hook neurons and head cephalic (CEM) neurons (PubMed:10517638, PubMed:11553327, PubMed:12411744, PubMed:15563610, PubMed:16943275, PubMed:16481400, PubMed:31264582). Expressed in the male tail (PubMed:26150102, PubMed:28745435). First expressed during L4 and peaks in the adult male. The transmembrane domains are sufficient for localization in the cilium. The cytoplasmic tails are necessary for localization in cell bodies and anchoring at the ciliary base. Cytoplasmic tails also regulate sensory function. Phosphorylated. CK2 (kin-3 and kin-10) and calcineurin act antagonistically to regulate the phosphorylation state. Worms exhibit defects in 2 aspects of male mating behavior: response to hermaphrodite contact and vulva location. Belongs to the polycystin family.