title: Identification of a glycogenolysis-inhibiting peptide from the corpora cardiaca of locusts.
abstract: A mass spectrometric study of the peptidome of the neurohemal part of the corpora cardiaca of Locusta migratoria and Schistocerca gregaria shows that it contains several unknown peptides. We were able to identify the sequence of one of these peptides as pQSDLFLLSPK. This sequence is identical to the part of the Locusta insulin-related peptide (IRP) precursor that is situated between the signal peptide and the B-chain. We designated this peptide as IRP copeptide. This IRP copeptide is also present in the pars intercerebralis, which is likely to be the site of synthesis. It is identical in both L. migratoria and S. gregaria. It shows no effect on the hemolymph lipid concentration in vivo or muscle contraction in vitro. The IRP copeptide is able to cause a decreased phosphorylase activity in locust fat body in vitro, opposite to the effect of the adipokinetic hormones and therefore possibly represents a glycogenolysis-inhibiting peptide.
authors.affiliation: Laboratory for Developmental Physiology and Molecular Biology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium. Elke.Clynen@bio.kuleuven.ac.be
authors.forename: Elke
authors.initials: E
authors.lastname: Clynen
authors.forename: Jurgen
authors.initials: J
authors.lastname: Huybrechts
authors.forename: Geert
authors.initials: G
authors.lastname: Baggerman
authors.forename: Jan
authors.initials: J
authors.lastname: Van Doorn
authors.forename: Dick
authors.initials: D
authors.lastname: Van Der Horst
authors.forename: Arnold
authors.initials: A
authors.lastname: De Loof
authors.forename: Liliane
authors.initials: L
authors.lastname: Schoofs
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006003:Glycogen / Q000378:metabolism*; D024981:Glycogen Phosphorylase / Q000037:antagonists & inhibitors; D006110:Grasshoppers; D007301:Insect Hormones / Q000494:pharmacology; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D009490:Neurosecretory Systems / Q000737:chemistry*; D011498:Protein Precursors / Q000737:chemistry; D020539:Sequence Analysis, Protein; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D004791:Enzyme Inhibitors; D007301:Insect Hormones; D009479:Neuropeptides; D011498:Protein Precursors; C014956:adipokinetic hormone (locust); D006003:Glycogen; D024981:Glycogen Phosphorylase