Ren, B.; Wang, Y.; Yu, Z.; Meng, T.; Yu, L.; Zhou, Y.; Que, T.; Wang, H.; He, M.; Li, Y.; Liu, L.; Liu, W.

The Sunda pangolin (Manis javanica) is a burrowing and nocturnal animal, and they have poor vision, thus, intraspecies communication relies on olfaction, such as mating, warning, and scent-marking. However, the intraspecies pheromone in pangolins remains unknown. In this study, all the odorant-binding proteins in Sunda pangolins were functionally expressed, and they were screened against a panel of 32 volatiles that were derived from the pangolin\'s urine, feces, and anal gland secretions. Reverse chemical ecology identified that M. javanica odorant-binding protein 3 (MjavOBP3) possesses the highest binding affinity to muscone. A subsequent behavior-tracking assay showed that only males can sense muscone; thus, we hypothesize that muscone is a male-specific scent-marking pheromone. Meanwhile, the structural study showed that Tyr117 contributes the most to muscone\'s binding, which was further validated by site-directed mutagenesis. The findings clarify the scent-marking mechanism in pangolins, and muscone could potentially be used to support the monitoring and conservation of this endangered animal.