title: Neurotensin-like immunoreactivity generated by pepsin from human plasma and gastric tissue.
abstract: The present study demonstrates precursors of neurotensin-like immunoreactivity (NTLI) endogenous to human gastric tissue and plasma, and the existence of a gastric NTLI-generating enzyme system. The molecular size of the NTLI-precursors in plasma and gastric tissue were estimated by gel permeation chromatography to be ca 50,000-60,000 and 60,000-70,000 Da, respectively. The neurotensin-like peptide generated from the precursor was detected with a carboxyl-terminally directed antiserum but did not cross-react with an amino-terminally directed antiserum. A neurotensin-like peptide isolated from pepsin-treated human plasma was characterized by mass spectrometry and its amino acid sequence determined. This novel nonapeptide, referred to as kinetensin, failed to affect pentagastrin-stimulated acid secretion or blood pressure in the rat. Sequence homologies between neurotensin, kinetensin and proteins of the serum albumin family suggest a common evolutionary origin and raise questions regarding albumin-like proteins as precursors of regulatory peptides.
mesh_terms: D000595:Amino Acid Sequence; D001794:Blood Pressure / Q000187:drug effects; D002850:Chromatography, Gel; D005744:Gastric Acid / Q000378:metabolism; D005748:Gastric Fundus / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009479:Neuropeptides / Q000097:blood / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism* / Q000494:pharmacology; D010434:Pepsin A / Q000494:pharmacology*; D011863:Radioimmunoassay
chemical_list: D009479:Neuropeptides; D009842:Oligopeptides; C031644:neurotensin-like immunoreactivity; C048812:kinetensin; D010434:Pepsin A