RGD Reference Report - The Bifunctional Rat Pancreatic Secretory Trypsin Inhibitor/Monitor Peptide Provides Protection against Premature Activation of Pancreatic Juice. - Rat Genome Database

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The Bifunctional Rat Pancreatic Secretory Trypsin Inhibitor/Monitor Peptide Provides Protection against Premature Activation of Pancreatic Juice.

Authors: Graf, R  Klauser, S  Fukuoka, SI  Schiesser, M  Bimmler, D 
Citation: Graf R, etal., Pancreatology 2003;3(3):195-206.
RGD ID: 724699
Pubmed: (View Article at PubMed) PMID:12771515
DOI: Full-text: DOI:10.1159/000070729

BACKGROUND: In the rat, two forms of the pancreatic secretory trypsin inhibitor, PSTI-I and PSTI-II, are secreted into pancreatic juice. It is assumed that their role is to protect the pancreas from premature activation of the protease-rich pancreatic juice. In the small intestine, PSTI-I, also called 'monitor peptide', is thought to have a different role: PSTI-I competes with protein for activated trypsin. In the presence of a protein-rich meal, free PSTI induces a release of cholecystokinine from the intestine. METHODS: To investigate whether its role as monitor peptide is compatible with the inhibitory, protective function in the pancreas, PSTI-I was chemically synthesized and then renatured. RESULTS: The peptide was almost completely trypsin resistant and exhibited a dose-dependent inhibitory activity to bovine and partially purified rat trypsin. Furthermore, experiments with trypsin- and endopeptidase-activated pancreatic juice demonstrated that its inhibitory capacity was sufficient to prevent premature activation. Binding studies of (125)I-labeled PSTI-I with the putative intestinal receptor using isolated membranes indicated the presence of high-affinity binding sites (k(d) = 5 x 10(-8)M). Binding of PSTI-I could be competed with excess PSTI-I or trypsin. In a biological assay system, injections of PSTI-I displayed monitor peptide activity by inducing a dose-dependent trypsinogen release from the pancreas. CONCLUSION: Our experiments support a dual function of PSTI-I: monitoring protein in the gut due to its 'moderate' affinity for trypsin and a protective role in the pancreas.

Annotation

Gene Ontology Annotations    

Biological Process

Molecular Function

Objects Annotated

Genes (Rattus norvegicus)
Mmp13  (matrix metallopeptidase 13)
Spink1  (serine peptidase inhibitor, Kazal type 1)


Additional Information