Auxiliary subunit of the NALCN sodium channel complex, a voltage-gated ion channel responsible for the resting Na(+) permeability that controls neuronal excitability. Activated by neuropeptides substance P, neurotensin, and extracellular calcium that regulates neuronal excitability by controlling the sizes of NALCN-dependent sodium-leak current. NALCN complex consists of NALCN and auxiliary subunits, UNC79, UNC80 and NACL1. These auxiliary subunits are essential for the NALCN channel function (By similarity). UNC80 bridges NALCN to UNC79 (By similarity). Belongs to the unc-79 family.