APHRODISIN - PHEROMONE OR TRANSDUCER

Aphrodisin, the major soluble protein in hamster vaginal discharge, is detected by receptors within the vomeronasal organ of the male hamster, and stimulates copulatory behavior. The loss of this effect on behavior after degradation of the protein with heat or proteolytic enzymes shows that the polypeptide chain is an essential part of the pheromone. Furthermore, attempts to remove small molecules from the protein have provided little indication of the presence of a transported ligand. However, the chemical and physical properties of the protein itself indicate that it could bind low molecular weight, water-insoluble compounds. The abundance, size, charge, and the primary structure of aphrodisin, when considered together, all indicate that it is a member of the recently recognized α-2u-globulin superfamily of extracellular proteins, some of which, such as serum retinol-binding protein and odorant-binding protein, are known to bind smaller molecules. Preliminary results from a study of the effects of bacterial aphrodisin, produced by molecular cloning in E.coli, on behavior indicate that the polypeptide backbone is only partially active and that post-translational modifications of the protein or the presence of an as yet undetected ligand may be necessary for full activity. © 1990 Oxford University Press.