Nonsulfated cholecystokinins in the small intestine of pigs and rats.

摘要: Abstract Cholecystokinin (CCK) is a gut hormone that acts via two receptors. The CCK A -receptor requires the tyrosyl residue in C-terminal bioactive site of to be O-sulfated, whereas, B binds irrespective sulfation. Consequently, unsulfated peptides – if present may constitute system only through -receptor. Therefore, we have now examined whether, occur nonsulfated form small intestine pigs and rats. concentrations sulfated were measured by RIAs, one specific for CCKs new two-step assay CCK. For further characterization, intestinal extracts subjected size- ion exchange-chromatography. highest duodenum proximal part jejunum both pig rat. porcine duodenal mucosa contained 193 ± 84 pmol/g 31 ± 10 pmol/g CCK, upper rat 70 ± 19 pmol/g 8 ± 2 pmol/g, respectively. degree sulfation correlated with endoproteolytic proCCK processing. Thus, 38% CCK-58 was unsulfated, 12% CCK-8 unsulfated. results show substantial rats are not sulfated, longer (CCK-58 CCK-33) less than shorter (CCK-22 CCK-8). Hence, demonstrate processed α -amidated which latter assumed act