Species variation in the tyrosine sulfation of mammalian gastrins

The degree of tyrosine sulfation and the distribution between gastrin-17- and gastrin-34-like immunoreactivity (LI) were studied in the antra of ten mammalian species. Specific radioimmunoassays, gel-, and ion-exchange chromatography as well as enzymatic cleavage with trypsin and arylsulfatase were used. The percentage of sulfation varied from 24.4 +/- 4.2 (mean +/- SEM) in dogs to 80.1 +/- 2.6 in sheep, 46.8 +/- 3.3 in humans, 50.1 +/- 3.2 in cows, 55.9 +/- 2.3 in rats, 57.4 +/- 3.1 in pigs, 61.3 +/- 2.2 in guinea pigs, 64.1 +/- 4.7 in cats, 64.8 +/- 2.1 in mice and 68.2 +/- 2.8 in rabbits. Gastrin-34-LI in antral extracts could be converted to gastrin-17-LI by trypsin in all species. Five percent of antral gastrins eluted as gastrin-34-LI in all species. We conclude that while the ratio of gastrin-34-LI to gastrin-17-LI varies little in mammals, large differences occur in the degree of sulfation.