1. Isolation and structure of corticostatin peptides from rabbit fetal and adult lung
Q Z Zhu, J Hu, S Mulay, F Esch, S Shimasaki, S Solomon Proc Natl Acad Sci U S A. 1988 Jan;85(2):592-6. doi: 10.1073/pnas.85.2.592.
A 34-amino acid peptide and three other structurally related peptides were isolated from rabbit fetal and adult lung. These cationic arginine- and cysteine-rich peptides inhibit corticotropin (ACTH)-stimulated rat adrenal cell corticosterone production. The peptide was called corticostatin (CSI). CSI was purified by reverse-phase HPLC and was shown to be homogenous from its amino acid analysis. Its sequence was determined on a gas-phase sequenator. The structure of CSI is Gly-Ile-Cys-Ala-Cys-Arg-Arg-Arg-Phe-Cys-Pro-Asn-Ser-Glu-Arg-Phe-Ser-Gly- Tyr-Cys - Arg-Val-Asn-Gly-Ala-Arg-Tyr-Val-Arg-Cys-Cys-Ser-Arg-Arg. CSI was found to markedly inhibit ACTH-stimulated corticosterone production by rat adrenal cells in vitro but did not affect basal levels. CSI did not affect the stimulation of aldosterone synthesis by angiotensin II in rat zona glomerulosa cells but it did suppress ACTH-stimulated aldosterone synthesis in whole adrenal cells, demonstrating that CSI is a specific inhibitor of ACTH-stimulated corticosteroid synthesis. The minimum effective concentration of CSI inhibiting ACTH-stimulated (33 pM) corticosterone production was 5 nM (20 ng/ml), the ED50 (50% effective dose) was 25 nM and steroidogenesis was completely inhibited at concentrations greater than 500 nM (2 micrograms/ml).
2. Novel tachykinins from the brain of the sea lamprey, Petromyzon marinus, and the skate, Raja rhina
D Waugh, S Sower, C Bjenning, J M Conlon Peptides. 1994 Jan;15(1):155-61. doi: 10.1016/0196-9781(94)90185-6.
Using radioimmunoassays for mammalian tachykinins, peptides with substance P-like immunoreactivity and neurokinin A-like immunoreactivity were identified in an extract of the brain of the longnose skate, Raja rhina (elasmobranch) but only a peptide with neurokinin A-like immunoreactivity was identified in the brain of the sea lamprey, Petromyzon marinus (agnathan). The primary structure of the skate peptide with substance P-like immunoreactivity (Ala-Lys-His-Asp-Lys-Phe-Tyr-Gly-Leu-Met-NH2) shows one amino acid substitution (Phe3-->His) compared with scyliorhinin I, previously isolated from dogfish brain and gut. The skate neurokinin A-related peptide (His-Lys-Leu-Gly-Ser-Phe-Val-Gly-Leu-Met-NH2) shows two substitutions (Thr3-->Leu and Asp4-->Gly) compared with mammalian neurokinin A. Although the COOH-terminus of the lamprey tachykinin (Arg-Lys-Pro-His-Pro-Lys-Glu-Phe-Val-Gly-Leu-Met-NH2) resembles neurokinin A, the presence of the strongly conserved Lys/Arg-Pro-Xaa-Pro motif at the NH2-terminus of the peptide indicates greater structural similarity with substance P. The additional arginine residue at position 1 in the peptide suggests that the lamprey is utilizing a site of posttranslational processing in the tachykinin precursor that is different from the equivalent site in mammalian and other lower vertebrate preprotachykinin(s).
3. Primary structures of glucagon and glucagon-like peptide isolated from the intestine of the parasitic phase lamprey Petromyzon marinus
J M Conlon, P F Nielsen, J H Youson Gen Comp Endocrinol. 1993 Jul;91(1):96-104. doi: 10.1006/gcen.1993.1109.
Immunohistochemical studies have indicated that glucagon-containing cells are present in the intestinal mucosa of the agnathan Petromyzon marinus (sea lamprey) but are absent from the pancreas. Glucagon was isolated from an extract of intestinal tissue taken from specimens of sea lamprey during their parasitic phase. The primary structure of the peptide was established as: His-Ser-Glu-Gly-Thr5-Phe-Thr-Ser-Asp-Tyr10-Ser-Lys-Tyr-Leu- Glu15-Asn-Lys-Gln-Ala-Lys20-Asp-Phe-Val-Arg-Trp25-Leu- Met-Asn-Ala. This amino acid sequence shows 8 substitutions compared with that of mammalian glucagon but, with the exception of the COOH-terminal alanine residue, lamprey gut glucagon contains no structural features that have not been previously seen in glucagons isolated from the pancreata of gnathostomes. The amino acid sequence of lamprey glucagon-like peptide (GLP) demonstrates that the primary structure of this peptide has been less well conserved than that of glucagon. The sequence His-Ala-Asp-Gly-Thr5-Phe-Thr-Asn-Asp-Met10-Thr-Ser-Tyr- Leu-Asp15-Ala-Lys-Ala-Ala-Arg20-Asp-Phe-Val-Ser-Trp25- Leu-Ala-Arg-Ser-Asp30- Lys-Ser shows 16 amino acid substitutions compared with the corresponding region of mammalian GLP-1 and 15 substitutions compared with that of salmon GLP.
