title: Processing of the L5-67 precursor peptide and characterization of LUQIN in the LUQ neurons of Aplysia californica.
abstract: Metabolic labeling of the dorsal Left Upper Quadrant (LUQ) cells of the abdominal ganglion of Aplysia californica and RP-HPLC separation of their peptide content allowed us to identify the L5-67 precursor and its processed peptides. Cleavage of the signal peptide occurred between amino acids 23 and 24 of the prepropeptide and generated a propeptide of 89 amino acids. Further processing by endopeptidases at the twin basic residues Lys12-Arg13 of the precursor generated a peptide of 76 amino acids, as well as an amidated decapeptide, LUQIN. The sequence of LUQIN was determined by amino acid sequencing and by its comigration with the synthetic peptide Ala-Pro-Ser-Trp-Arg-Pro-Gln-Gly-Arg-Phe-amide in three different RP-HPLC systems. The amidation of LUQIN was further demonstrated by its resistance to carboxypeptidase A digestion.
authors.affiliation: Department of Biochemistry, University of Montreal, Canada.
authors.forename: R S
authors.initials: RS
authors.lastname: Aloyz
authors.forename: L
authors.initials: L
authors.lastname: DesGroseillers
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001048:Aplysia; D002851:Chromatography, High Pressure Liquid; D017952:Ganglia, Invertebrate / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D009479:Neuropeptides / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D011392:Proline / Q000378:metabolism; D011498:Protein Precursors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011865:Radioisotope Dilution Technique; D013462:Sulfur Radioisotopes; D014316:Tritium
chemical_list: C094043:LUQIN; D009479:Neuropeptides; D011498:Protein Precursors; D013462:Sulfur Radioisotopes; D014316:Tritium; D011392:Proline; D008715:Methionine; D007930:Leucine