Binds pheromones, the pheromones are released from the saliva of males and affect the sexual behavior of females. Homodimer. In the submaxillary salivary glands of mature male pigs, but absent from that of females. Expression was much lower in submaxillary glands of castrated male pigs than in sexually mature individuals. Two isoforms have been identified which differ by 3 residues. Belongs to the calycin superfamily. Lipocalin family.