Vasotocin and Isotocin Precursors from the White Sucker, Catostomus commersoni: Cloning and Sequence Analysis of the cDNAs

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 86; no. 14; pp. 5242 - 5246
• Main Authors: Heierhorst, Jörg, Morley, Steven D., Figueroa, Jaime, Krentler, Christiane, Lederis, Karl, Richter, Dietmar
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.07.1989; National Acad Sciences
• Subjects: Amino Acid Sequence; Amino acids; Animals; Arginine Vasopressin - genetics; Base Sequence; Catostomus commersoni; Cloning, Molecular; Complementary DNA; DNA; DNA - genetics; DNA-Directed DNA Polymerase; Fishes - genetics; Freshwater; Gene Amplification; Genes; Genomics; Hormones; Humans; Molecular Sequence Data; Neurophysins; Nucleic acid precursors; Oligonucleotides; Oxytocin - analogs & derivatives; Oxytocin - genetics; Protein precursors; Protein Precursors - genetics; RNA; Sequence Homology, Nucleic Acid; Vasotocin - genetics
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.86.14.5242

The nucleotide sequences of cloned cDNAs encoding the precursors for vasotocin and isotocin have been elucidated by analyzing a λ gt11 library constructed from poly(A)+ RNA from the hypothalamic region of the teleost fish Catostomus commersoni. Screening of the library was carried out with synthetic oligonucleotide probes deduced from the amino acid sequences of the nonapeptides vasotocin and isotocin. The cDNA nucleotide sequences predict isotocin and vasotocin prohormone precursors each consisting of a signal peptide, a hormone moiety, and a neurophysin-like molecule. However, in comparison to their mammalian counterparts, both fish neurophysins are extended at their C termini by an ≈ 30 amino acid sequence with a leucine-rich core segment. These extensions show striking similarities with the glycopeptide moiety (the so-called copeptin) present in mammalian vasopressin precursors, except that they lack the consensus sequence for N-glycosylation. These data suggest that mammalian copeptin is derived from the C terminus of an ancestral neurophysin.