Auxilary subunit of the NALCN channelosome complex, which regulates the resting membrane potential by depolarizing sodium leak currents (PubMed:32494638, PubMed:35387979, PubMed:34929720). The NALCN channelosome complex is a voltage-gated ion channel responsible for the resting Na(+) permeability that controls neuronal excitability (PubMed:35387979, PubMed:34929720). The NALCN channelosome is constitutively active and conducts monovalent cations but is blocked by physiological concentrations of extracellular divalent cations (PubMed:32494638). Activated by neuropeptides substance P, neurotensin, and extracellular Ca(2+) that regulates neuronal excitability by controlling the sizes of NALCN-dependent sodium-leak current (PubMed:32494638). UNC80 is also essential for NALCN sensitivity to extracellular Ca(2+) (PubMed:32494638). {ECO:0000269|PubMed:32494638, ECO:0000269|PubMed:34929720, ECO:0000269|PubMed:35387979}. This is the function of UNC80 (unc-80 subunit of NALCN channel complex, ENSG00000144406).