A specific binding of the cholecystokinin-releasing peptide (monitor peptide) to isolated rat small-intestinal cells

• DOI: 10.1042/bj2910057
• Publication Date: 2015-08-10T21:32:05Z
• Authors: R Yamanishi; J Kotera; T Fushiki; T Soneda; T Saitoh; T Oomori; T Satoh; E Sugimoto
• Keywords: Trypsin inhibitor

A specific binding of the cholecystokinin (CCK)-releasing peptide (monitor peptide) to isolated rat jejunal mucosal cells was investigated. The 125I-labelled purified monitor bound cells, and a large excess amount non-labelled inhibited binding. completed within 60 min at 37 degrees C. optimum pH for 8-9. Scatchard plot linear, dissociation constant 50 nM. density monitor-peptide-binding sites high in duodenum but low ileal absent colonic mucosa. recombinant four kinds point mutants it were prepared. mutant peptides indicated that only trypsin inhibitor could bind cells. Human pancreatic secretory binding, other inhibitors, i.e. bovine basic inhibitor, soybean egg-white leupeptin, antipain FOY-305, did not affect all. These findings suggested site on has trypsin-like specificity, exhibiting special specificity pancreatic-secretory-trypsin-inhibitor family. Autoradiography an affinity-cross-linked complex intact its molecular mass 33 kDa or 53 presence absence 2-mercaptoethanol respectively.