title: Lateral enzyme topology in the rough endoplasmic reticulum of rat liver.
abstract: Rough microsomes were subfractionated on the basis of different properties in order to investigate the nature and extent of the enzyme heterogeneity of these vesicles. A discontinuous gradient, containing monovalent cations allowed the separation of a ribosome-poor membrane fraction which was enriched in electron transport enzymes and relatively poor in phosphatases. Zonal centrifugation on a stabilizing gradient separated 3 fractions characterized by enrichment of electron transport enzymes, glucose-6-phosphatase and adenosinetriphosphatase, respectively. An essentially similar pattern was seen when ribosomes were removed with EDTA and the denuded vesicles subfractionated on a sucrose gradient. Rough microsomes from phenobarbital-treated rats exhibited the same pattern both qualitatively and quantitatively. It appears that electron transport enzymes and two types of phosphatases are heterogeneously distributed among rough microsomal vesicles.
mesh_terms: D000818:Animals; D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient; D002501:Centrifugation, Zonal; D003579:Cytochrome Reductases / Q000032:analysis; D004492:Edetic Acid; D008055:Lipids / Q000032:analysis; D008099:Liver / Q000201:enzymology; D008297:Male; D008851:Micropore Filters; D008862:Microsomes, Liver / Q000032:analysis / Q000201:enzymology*; D010634:Phenobarbital / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000032:analysis; D011506:Proteins / Q000032:analysis; D051381:Rats; D011952:Receptors, Concanavalin A / Q000032:analysis; D012270:Ribosomes / Q000201:enzymology
chemical_list: D008055:Lipids; D011506:Proteins; D011952:Receptors, Concanavalin A; D004492:Edetic Acid; D003579:Cytochrome Reductases; D010744:Phosphoric Monoester Hydrolases; D010634:Phenobarbital