Identification of MSEL and VLDV neurophysins in human pituitary gland

Identification of human neurophysins: complete amino acid sequences of MSEL- and VLDV-neurophysins

Two human neurophysins have been purified from acetone-desiccated posterior pituitaries by acidic extraction, molecular sieving, and ion-exchange chromatography. The complete amino acid sequence of each protein has been determined by using a sequencer and characterizing two sets of overlapping enzymic peptides. The two neurophysins belong to two structural families previously defined as MSEL- and VLDV-neurophysins according to the nature of the residues in positions 2, 3, 6, and 7. (MSEL-neurophysins contain methionine-2, serine-3, glutamic acid-6, and leucine-7; VLDV-neurophysins contain valine-2, leucine-3, aspartic acid-6, and valine-7.) Human MSEL-neurophysin has only 93 residues instead of 95 usually found in MSEL-neurophysins from other mammalian species, probably because of a deletion of amino acids 91 and 92. Compared with bovine MSEL-neurophysin, nine variations (seven substitutions and two deletions) are observed. Human VLDV-neurophysin has 93 residues, as do the other mammalian VLDV-neurophysins. There are 11 substitutions when the comparison is made with bovine VLDV-neurophysin. Between the two human neurophysins, there are 26 variations. However, the central parts of the proteins (residues 10-70) are nearly identical. Furthermore, in this region identical substitutions are found in positions 29 and 60 of both neurophysins, suggesting either a single exon or some relationship between the two corresponding genes.

Phylogeny of neurohypophyseal hormones. Vasopressin polymorphism in three kangaroo species

The neurohypophyseal hormones of three species of Australian marsupials belonging to the family Macropodidae (Macropus rufus, Macropus giganteus, Macropus robustus) have been investigated. In these species three active peptides have been disclosed, one with oxytocic activity and two with pressor activity. The three hormones are present in all the individual glands which have been examined. Purification has been undertaken by ion-exchange chromatography and paper chromatoelectrophoresis. The more abundant of the pressor hormones (about 80% of the total pressor activity) has been identified as lysine-vasopressin by its biological properties, its chromatographic behaviour and its amino acid composition. The second pressor principle, more basic, has not yet been chemically characterized but its pharmacological properties and its chromatographic behaviour suggest that it is closely related or identical to arginine-vasopressin. Dimorphism of vasopressins seems peculiar to Metatheria since it has not been observed in Protheria and very rarely in Eutheria.