Immunological identification of rat neurophysin precursors

Abstract

NEURONES in the supraoptic and paraventricular nuclei of the hypothalamus synthesise two peptide hormones, vasopressin and oxytocin. These hormones and their neurophysin ‘carrier’ proteins are stored in (and released from) nerve endings in the posterior lobe of the pituitary^1–3. On the basis of extensive studies of the synthesis of vasopressin in vivo and in vitro, Sachs et al.^4–8 have suggested that vasopressin and its associated neurophysin are synthesised as parts of a common precursor by a ribosomal mechanism. We have also presented evidence that the neurophysins are synthesised as parts of larger precursor molecules^9,10. These 20,000 molecular weight precursors seem first to give rise to 17,000 molecular weight intermediates which, in turn, yield the 12,000 molecular weight neurophysins. The following data show that the putative neurophysin precursors and intermediates bind specifically to anti-rat neurophysin antiserum.