Neurophysins: Molecular and Cellular Aspects

Neurophysins are linear cystine‐rich proteins containing 93–95 amino acid residues which like the neurohypophysial hormones oxytocin and vasopressin are formed in the hypothalamus and travel from there to the hypophysial posterior lobe. A species usually contains two (or three) neurophysins which differ only slightly in chain length and/or sequence. Many observatios suggest that both oxytocin and one of the neurophysins as well as vasopressin and the other neurophysin have a common precursor whose long chain is split into neurophysin and hormone. It can be shown on rats having considerable diabetes insipidus that a single gene controls the biosynthesis of the vasopressin and one of the neurophysins. Transport of the peptide hormones oxytocin and vasopressin from the hypothalamus to the hypophysial posterior lobe involves the neurophysins, which are proteins made up of ca. 95 amino acid residues. Biosynthesis and transformation of secretory proteins (pro‐ and prepro‐proteins) are gradually being unraveled by present‐day research.