Distribution of cell surface saccharides on pancreatic cells

Abstract

We describe here a simple, general procedure for the purification of a variety of lectins, and for the preparation of lectin4erritin conjugates of defined molar composition and binding properties to be used as probes for cell surface saccharides. The technique uses a "universal" affinity column for lectins and their conjugates, which consists of hog sulfated gastric mucin glycopeptides covalently coupled to agarose. The procedure involves: (a) purification of lectins by chromatography of aqueous extracts of seeds or other lectin-containing fluids over the affinity column, followed by desorption of the desired lectin with its hapten sugar; (b) iodination of the lectin to serve as a marker during subsequent steps; (c) conjugation of lectin to ferritin with glutaraldehyde; (d) collection of active lectin-ferritin conjugates by affinity chromatography; and (e) separation of monomeric lectin-ferritin conjugates from larger aggregates and unconjugated lectin by gel chromatography. Based on radioactivity and absorbancy at 310 nm for lectin and ferritin, respectively, the conjugates consist of one to two molecules of lectin per ferritin molecule. Binding studies of native lectins and their ferritin conjugates to dispersed pancreatic acinar cells showed that the conjugation procedure does not significantly alter either the affinity constant of the lectin for its receptor on the cell surface or the number of sites detected.KEY WORDS lectin affinity purificationmucin peptides 9 lectin-ferritin conjugates conjugate binding characteristics Because of their high specificity of binding to the carbohydrate moieties of glycoproteins and glycolipids, lectins have proven to be powerful tools for examination of the architecture of the plasmalemma, comparison of the surface saccbaride patterns of normal and transformed cells, and detection of cell surface changes during development (15). For these purposes, a variety of lectins with different sugar specificities have been purified by either conventional procedures or by affinity chromatographic (15) techniques applicable to individual iectins. In addition, several general affinity adsorbents have been proposed for isolation of groups of lectins. For example, fixed erythrocytes J. CELL BIOLOGY 9 The Rockefeller University Press -0021-

Review Article. Interactions of Determinants in the Ontogeny of the Gastrointestinal Tract: a Unified Concept

“…It is not known whether morphogenesis and differentiation lead to a change in membrane properties, or if the change in membrane properties results in morphogenesis and differentiation. Studies of the pancreas showed that acinar cells strongly bind alliectins; on the other hand, endocrine and centroacinar cells selectively bind only certain specific lectins(60). The characteristics of these lectin receptors have been found to change during development of the…”

Genetic Endowment, Biological Clocks, Regulatory Mechanism, and Environmental Influences as Determinants Affecting Ontogeny of the Gastrointestinal Tract

“…To date, no direct cause and effect association has been reported, but alterations in membrane properties primarily lectin binding, have been documented in the pancreas (15,16) and small intestine (17).…”

Ontogeny of the Exocrine Pancreas

“…In f ur t he r mo r e , th e c h a r n c t e r i s t 'i c s o f l e ctin b indin g h .i v o h l'L'Il lo u n d t o ,' h; lI1gL~d uri nu d cvo l opm cn t o f th e rat pnrr -.r c-n t i c-:]C iIl;lr (' vlls (10).…”