title: Processing and targeting of a molluscan egg-laying peptide prohormone as revealed by mass spectrometric peptide fingerprinting and peptide sequencing.
abstract: The neuroendocrine cerebral caudodorsal cells of Lymnaea stagnalis initiate and coordinate ovulation and egg mass production and associated behaviors through the release of a complex set of peptides that are derived from the caudodorsal cell hormone-I (CDCH-I) precursor. We have previously characterized the CDCH-I peptide. In the present study, we isolated and amino acid sequenced by conventional peptide chemistry five additional peptides, epsilon-peptide, calfluxin, alpha-caudodorsal cell peptide, delta-peptide, and carboxyl-terminally located peptide, from the cerebral commissure, the neurohemal area of the caudodorsal cells. Fingerprinting by matrix-assisted laser desorption mass spectrometry of peptides in the commissure demonstrated the presence of all sequenced peptides and, in addition, could identify two other peptides derived from pro-CDCH-1, the beta 1- and beta 3-peptides. These findings together with previous immunocytochemical studies enabled us to define cleavage sites and major processing events of pro-CDCH-1. Pro-CDCH-1 is initially cleaved in the Golgi apparatus into carboxyl- and amino-terminal parts, each of which is sorted into distinct vesicle classes that traffic to different intracellular sites. As a result, in the commissure, peptides derived from the carboxyl-terminal part, including CDCH-1, are present at a many-fold higher concentration than those derived from the amino-terminal part.
authors.affiliation: Graduate School Neurosciences Amsterdam, Research Institute Neurosciences Vrije Universiteit, Faculty of Biology, The Netherlands.
authors.forename: K W
authors.initials: KW
authors.lastname: Li
authors.forename: C R
authors.initials: CR
authors.lastname: Jiménez
authors.forename: P A
authors.initials: PA
authors.lastname: Van Veelen
authors.forename: W P
authors.initials: WP
authors.lastname: Geraerts
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D007447:Invertebrate Hormones / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008195:Lymnaea; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D014020:Tissue Extracts / Q000378:metabolism
chemical_list: D007447:Invertebrate Hormones; D011498:Protein Precursors; D014020:Tissue Extracts; C026880:egg-laying hormone, Mollusca