Aphrodisin: pheromone or transducer?

Aphrodisin, the major soluble protein in hamster vaginal discharge,is detected by receptors within the vomeronasal organ of themale hamster, and stimulates copulatory behavior. The loss ofthis effect on behavior after degradation of the protein withheat or proteolytic enzymes shows that the polypeptide chainis an essential part of the pheromone. Furthermore, attemptsto remove small molecules from the protein have provided littleindication of the presence of a transported ligand. However,the chemical and physical properties of the protein itself indicatethat 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 ofthe recently recognized -2u-globulin superfamily of extracellularproteins, some of which, such as serum retinol-binding proteinand odorant-binding protein, are known to bind smaller molecules.Preliminary results from a study of the effects of bacterialaphrodisin, produced by molecular cloning in E.coli, on behaviorindicate that the polypeptide backbone is only partially activeand that post-translational modifications of the protein orthe presence of an as yet undetected ligand may be necessaryfor full activity.     

Prion: disease or relief?

The self-perpetuating amyloid isoform, or prion, of the yeast translation termination factor eRF3 modulates programmed translational frameshifting that controls a regulatory circuit determining the polyamine levels in a yeast cell. But it is still unclear whether this effect is adaptive or pathological.     

Dendrites: bug or feature?

The integrative properties of dendrites are determined by a complex mixture of factors, including their morphology, the spatio-temporal patterning of synaptic inputs, the balance of excitation and inhibition, and neuromodulatory influences, all of which interact with the many voltage-gated conductances present in the dendritic membrane. Recent efforts to grapple with this complexity have focused on identifying functional compartments in the dendritic tree, the number and size of which depend on the aspect of dendritic function being considered. We discuss how dendritic compartments and the interactions between them help to enhance the computational power of the neuron and define the rules for the induction of synaptic plasticity.