title: Endoproteolysis of glucagon-like peptide (GLP)-1 (7-36) amide by ectopeptidases in RINm5F cells.
abstract: This study concerns whether the pancreatic beta cell expresses cell-surface ectopeptidases that are capable of proteolysis of peptide hormones and neuropeptides that modify glucose-dependent insulin release. These biochemical investigations of the RINm5F cell line found that these cells express ectopeptidases. We have characterized the limited endoproteolysis of GLP-1 (7-36) amide that occurs in the presence of RINm5F plasma membranes. The products and the sensitivity to specific peptidase inhibitors of the proteolysis is characteristic of neutral endopeptidase (NEP) 24.11. Vasoactive intestinal polypeptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP), amylin, glucagon, glucose-dependent insulinotropic polypeptide (GIP), and exendin-4 also undergo proteolysis in the presence of RIN cell membranes. NEP 24.11-activity in RIN cell membranes was confirmed using a specific fluorogenic assay, by histochemistry, and by comparison with the recombinant enzyme with respect to the kinetics of proteolysis of GLP-1 (7-36) amide and of a fluorogenic substrate. Specific fluorogenic assays revealed the presence of aminopeptidase N and the absence of aminopeptidase A and of dipeptidylpeptidase IV.
authors.affiliation: Institute of Physiology, Philipps University of Marburg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Hupe-Sodmann
authors.forename: R
authors.initials: R
authors.lastname: Göke
authors.forename: B
authors.initials: B
authors.lastname: Göke
authors.forename: H H
authors.initials: HH
authors.lastname: Thole
authors.forename: B
authors.initials: B
authors.lastname: Zimmermann
authors.forename: K
authors.initials: K
authors.lastname: Voigt
authors.forename: G P
authors.initials: GP
authors.lastname: McGregor
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D005768:Gastrointestinal Hormones; D005934:Glucagon / Q000378:metabolism*; D052216:Glucagon-Like Peptide 1; D004763:Glucagon-Like Peptides; D006868:Hydrolysis; D007340:Insulinoma; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D014407:Tumor Cells, Cultured
chemical_list: D005768:Gastrointestinal Hormones; D010446:Peptide Fragments; C055453:glucagon-like peptide 1 (7-36)amide; D004763:Glucagon-Like Peptides; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D010447:Peptide Hydrolases