Binding studies of 125I-TFF1 homodimer with gastric mucins. Autoradiography was obtained after incubating 125I-TFF1 homodimer with different fractions purified (B5-C2/C3) by size exclusion chromatography from (A) human gastric mucins,41 (B) reduced porcine gastric mucins,40 and (C) gastric mucins from X. laevis.42 These fractions were separated by non-denaturing agarose gel electrophoresis which was directly blotted on a nitrocellulose membrane. Reactivity with GSA-II, a lectin from Griffonia simplicifolia, confirms the presence of mucins since it recognises αGlcNAc (α1,4-linked N-acetylglucosamine), a conserved carbohydrate motif in gastric mucins.