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Title: Metabolism of recombinant progastrin in sheep.
Austin Authors: Paterson, Adrienne C;Baldwin, Graham S;Shulkes, Arthur
Affiliation: Department of Surgery, University of Melbourne, Austin, and Repatriation Medical Centre, Melbourne, Victoria 3084, Australia
Issue Date: 1-Sep-2002
Publication information: American Journal of Physiology. Endocrinology and Metabolism; 283(3): E449-56
Abstract: Precursor forms of peptide hormones may be biologically active with effects distinct from the mature end product. Nonamidated progastrin-derived peptides stimulate growth of colonic epithelium and are elevated in the circulation of patients with colorectal carcinomas, whereas the amidated end product is the major regulator of gastric acidity. Using region-specific radioimmunoassays, we here compared the in vitro and in vivo metabolism of recombinant human progastrin-(6-80) and two other nonamidated gastrins, gastrin-17-Gly and Tyr(70)-progastrin-(71-80). Although progastrin-(6-80) was very stable in vitro, both progastrin-(6-80) and gastrin-17-Gly were degraded in vivo. The in vivo data were best fitted by a double-exponential decay curve, and the half-lives for progastrin-(6-80) (t1/2alpha = 5.1 +/- 1.1, t(1/2)beta = 42 +/- 11 min) were significantly (P < 0.05) longer than for gastrin-17-Gly (t(1/2)alpha = 2.2 +/- 0.6, t(1/2)beta = 13 +/- 1 min). Tyr(70)-progastrin-(71-80) was degraded more rapidly. Comparison with amidated gastrins suggests that peptide length, rather than sequence, is the critical determinant of clearance. Progastrin has the clearance characteristics to be considered a circulating hormone.
Gov't Doc #: 12169437
DOI: 10.1152/ajpendo.00042.2002
Journal: American journal of physiology. Endocrinology and metabolism
Type: Journal Article
Subjects: Animals
Peptide Fragments.blood
Protein Precursors.blood.chemistry
Recombinant Proteins.blood
Appears in Collections:Journal articles

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