Enables interleukin-12 alpha subunit binding activity. Involved in natural killer cell activation involved in immune response and sensory perception of pain. Located in extracellular space. Part of interleukin-12 complex. Human ortholog(s) of this gene implicated in asthma; chronic obstructive pulmonary disease; immunodeficiency 29; and salmonellosis. Orthologous to human IL12B (interleukin 12B). [provided by Alliance of Genome Resources, Apr 2022]