Identity and regulation of stored and secreted progastrin-derived peptides in sheep

Abstract

Amidated and nonamidated progastrin-derived peptides have distinct biological activities that are mediated by a range of receptor subtypes. The objective was to determine the nature of the stored and secreted progastrin-derived peptides and to investigate whether progastrin release is regulated by gastric acidity. Using an antiserum directed to the C terminus of progastrin for identification and to monitor purification, C-terminal flanking peptides (CTFP) of progastrin (prog76-83, prog77-83, and prog78-83 in approximately equivalent amounts) were isolated and identified from extracts of sheep antrum using ion exchange, HPLC, and mass spectrometry. Only trace amounts of full-length progastrin..