Molecular Evolution of Neurohypophyseal Hormones and Neurophysins

Following the discovery of the pressor, oxytocic, and antidiu­ retic activities in posterior pituitary powders, about seventy years ago, two opposing views were held about the number of molecules responsible for these activities. According to the unitary conception, defended by ABEL, MAC ARTHUR, and later by VAN DYKE, a single protein displayed all these biologic proper­ ties; this so-called "mother-molecule" would be extracted from the gland under mild conditions and isolated by fractionated salt precipitation. In contrast, the multimolecule conception led DUDLEY, KAMM, and later DU VIGNEAUD, FROMAGEOT, and their co-workers to purify and characterize two active geptides from mammalian glands, the one, oxytocin, possessing oxytocic and milk-ejecting activities, the other vasopressin, possessing the pressor and antidiuretic activities. The question arose whether the actual hormone was the protein, the peptides being only cleavage products, or whether oxytocin and vasopressin were natural hormones. In 1955, we showed that the multiactive protein of the ox was