An enriched preparation of basal-lateral plasma membranes from gastric glandular cells

A procedure is described for the preparation of a membrane fraction enriched in basal-lateral plasma membranes from gastric mucosa. Gastric glands isolated from rabbit were employed as starting material, greatly reducing contamination from non-glandular cell types. The distribution of cellular components during the fractionation procedure was monitored with specific marker enzymes. (Na+ + K+)-ATPase, ouabain-sensitive K+-stimulated p-nitrophenyl-phosphatase and histamine-stimulated adenylate cyclase were used as markers for basal-lateral membranes. These three markers were similarly distributed during both differential and equilibrium density gradient centrifugation. The enriched membrane fraction contained more than 30% of the total initial activities of the three basal-lateral membrane markers which were purified better than 11-fold with respect to protein. (Na+ + K+)-ATPase activity was resolved from the activities of acid phosphatase, pepsin, Mg2+-ATPase, cytochrome c oxidase, NADPH-cytochrome c reductase, glucose-6-phosphatase, (K+ + H+)-ATPase, DNA and RNA.