title: Endoplasmic reticulum membrane isolated from small-intestinal epithelial cells: enzyme and protein components.
abstract: Endoplasmic reticulum membrane-rich fraction was obtained by subfractionation of the light microsomes from mouse jejunal mucosal epithelial cells. It was marked by high glucose-6-phosphatase, NADPH-cytochrome c reductase, and NADH-cytochrome c reductase activities and low Na+,K+-ATPase activity. The enrichment of Na+,K+-ATPase was 180-fold higher in the basolateral membranes than in the endoplasmic reticulum membrane-rich fraction relative to glucose-6-phosphatase. The protein peak that was phosphorylated in a Na-dependent manner was prominent in the basolateral membranes while it was a minor peak in the endoplasmic reticulum membrane-rich fraction. Under the electron microscope the fraction was seen to be composed of homogeneous small vesicles with thin smooth membranes.
mesh_terms: D000818:Animals; D002499:Centrifugation, Density Gradient; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000032:analysis*; D004848:Epithelium / Q000032:analysis; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D007413:Intestinal Mucosa / Q000032:analysis*; D007425:Intracellular Membranes / Q000032:analysis; D007583:Jejunum / Q000032:analysis*; D051379:Mice; D008854:Microscopy, Electron; D009245:NADH Dehydrogenase / Q000378:metabolism; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D010766:Phosphorylation; D011506:Proteins / Q000032:analysis; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D011506:Proteins; D009251:NADPH-Ferrihemoprotein Reductase; D009245:NADH Dehydrogenase; D005952:Glucose-6-Phosphatase; D000254:Sodium-Potassium-Exchanging ATPase