title: Isolation and chemical characterization of a novel insulin-related neuropeptide from the freshwater snail, Lymnaea stagnalis.
abstract: A novel molluscan insulin-related peptide (MIP) III, has been isolated from alcohol extracts of the neurohaemal area of the cerebral neuroendocrine light-green neurones of Lymnaea stagnalis. MIP III was purified by sequential high-performance gel-permeation chromatography followed by reverse-phase HPLC. MIP III is a heterodimer connected by disulphide bonds. Edman degradation analysis and subsequent alignment with the A and B chains of the previously identified MIP I and II showed that the 24-amino-acid peptide with the sequence pQSRPSIVC(E)CCFNQCTVQ(E)LLAYC represents the MIP III A chain, and the 37-amino-acid peptide sequence TTQHTCSILSRPHPRGLCGSTLANMVQWLCSTYTTSS the B chain. The overall amino acid sequence of MIP III shows about 50% similarity with those of MIP I and II, and only 20-40% similarity with other peptides of the insulin superfamily. Important structural features, e.g. disulphide bridges and the hydrophobic core, are conserved in MIP III.
authors.affiliation: Faculty of Biology, Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: K W
authors.initials: KW
authors.lastname: Li
authors.forename: W P
authors.initials: WP
authors.lastname: Geraerts
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004220:Disulfides / Q000032:analysis; D006801:Humans; D007202:Indicators and Reagents; D008195:Lymnaea / Q000737:chemistry*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009474:Neurons / Q000737:chemistry; D009479:Neuropeptides / Q000737:chemistry* / Q000302:isolation & purification; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004220:Disulfides; D007202:Indicators and Reagents; D046911:Macromolecular Substances; D009479:Neuropeptides; C063879:insulin-related neuropeptide