Complete amino acid sequence of a VLDV-type neurophysin from ostrich differs markedly from known mammalian neurophysins |
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Authors: | C Lazure H S Saayman R J Naudé W Oelofsen M Chrétien |
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Institution: | Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Canada. |
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Abstract: | The neurohypophyseal hormones vasopressin and oxytocin are known to be synthesized in eutherian mammals as part of larger precursors containing either MSEL- or VLDV-neurophysins. A neurophysin has been isolated from ostrich neurohypophyses and shown by partial amino acid sequence determination to be related to mammalian VLDV-neurophysin. The present report describes the complete amino acid sequence of this ostrich neurophysin containing 93 residues. This amino acid sequence, the first reported in birds, differs in a remarkable manner from its mammalian homolog. Indeed, it contains a large number of substitutions, including one insertion, distributed throughout the polypeptide chain when compared to known VLDV-neurophysins. Whereas many of these substitutions are localized inside the so-called constant region of the neurophysin, the highest variation can be found in the COOH-terminal region. |
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