The golden hamster aphrodisin gene. Structure, expression in parotid glands of female animals, and comparison with a similar murine gene.

The so-called lipocalins are a family of extracellular proteins that are known to typically fulfill tasks as transport proteins for small hydrophobic molecules. However, in the last decade, a large diversity has been described concerning their functions, for example as enzymes, immunomodulators, or proteins involved in coloration and pheromone action. Aphrodisin belongs to those lipocalins, which are of significant importance for the pheromonal stimulation of copulatory behavior in male hamsters. We recently succeeded in characterizing the corresponding cDNA and demonstrated the expression of the aphrodisin gene in the vagina, uterus, and Bartholin's glands of female hamsters. Here we report the structure of the aphrodisin gene and the functionality of its promoter region. We further compare the aphrodisin gene to the related gene for mouse odorant-binding protein 1a, indicating similar functions of their products. As a novelty, we show that the aphrodisin gene, in addition to the above-mentioned tissues, is also expressed in female hamster parotid glands. In contradiction to the results expected, we finally demonstrate that aphrodisin already occurs in vaginal discharge before the female animals reach fertility. These findings may lead to the identification of as yet unknown aphrodisin functions.