title: The Mr 80,000 common forms of neurophysin and vasopressin from bovine neurohypophysis have corticotropin- and beta-endorphin-like sequences and liberate by proteolysis biologically active corticotropin.
abstract: We have tested the hypothesis that the high M(r) forms common to both neurophysin and vasopressin detected in bovine neurohypophysis extracts (Nicolas, P., Camier, M., Lauber, M., Masse, M.-J. O., Möhring, J. & Cohen, P. (1980) Proc. Natl. Acad. Sci. USA 77, 2587-2591) might also contain the sequences of other known neuropeptides. The following evidence indicates that corticotropin- and beta-endorphin-like sequences are associated with similar high M(r) forms and are included in these M(r) 80,000 molecules. During the fractionation steps of high M(r) material, both corticotropin and beta-endorphin immunoreactive species were found to coelute with the neurophysin and vasopressin ones, either under M(r) 140,000 (in 0.1 M formic acid) or M(r) 70,000-80,000 (in 6 M guanidine) elution volumes. Corticotropin immunoreactivity was found to cofocus at pIs 6.05 and 5.8 with the M(r) 80,000 neurophysin-containing species. This material was submitted to affinity chromatography on purified anti-neurophysin antibodies covalently attached to Sepharose 4B. Both the corticotropin and beta-endorphin immunoreactivities, together with the neurophysin and vasopressin immunoreactivities, were retained on the immunoadsorbent and codesorbed by either a drastic pH change or by selective displacement with an excess of neurophysin. Comparison of the tryptic-digest maps of either the M(r) 68,000 fragment immunoprecipitated by anti-corticotropin antibodies or the M(r) 68,000 fragment released after precipitation of the M(r) 80,000 species by anti-neurophysin antibodies indicated large sequence homologies. Exposure of either the M(r) 80,000 or 68,000 components to mild proteolytic activities resulted in the formation of lower-size fragments. The resulting corticotropin-like immunoreactive material, recovered under the elution volume of standard (125)I-labeled corticotropin-(1-24), was tested for its ability to activate glucocorticoid biogenesis by the amphibian interrenal tissue (adrenal) in perifusion. It was found to exhibit a noticeable activity qualitatively undistinguishable from the one of the reference human corticotropin-(1-39). The name neurohypophyseal "coenophorin" (from the Greek word for common) is proposed for this class of M(r) 80,000 polypeptides that might represent the common precursor store-house for a set of neuropeptides produced in the hypothalamo-neurohypophyseal tract.
mesh_terms: D000311:Adrenal Glands / Q000187:drug effects; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D002417:Cattle; D002846:Chromatography, Affinity; D004723:Endorphins; D008970:Molecular Weight; D009481:Neurophysins / Q000494:pharmacology; D010446:Peptide Fragments / Q000032:analysis; D010904:Pituitary Gland, Posterior / Q000032:analysis*; D011863:Radioimmunoassay; D011898:Ranidae; D014667:Vasopressins / Q000494:pharmacology; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D009481:Neurophysins; D010446:Peptide Fragments; D014667:Vasopressins; D001615:beta-Endorphin; D000324:Adrenocorticotropic Hormone