ARTICLE

ANALYTICAL STUDY OF MICROSOMES AND ISOLATED SUBCELLULAR MEMBRANES FROM RAT LIVER

Henri Beaufay ¹, Alain Amar-Costesec ¹, Denise Thinès-Sempoux ¹, Maurice Wibo ¹, Mariette Robbi ¹, and Jacques Berthet ¹

¹ From the Laboratoire de Chimie Physiologique, Université de Louvain, Louvain, Belgium

Rat liver microsomal fractions have been equilibrated in various types of linear density gradients. 15 fractions were collected and assayed for 27 constituents. As a result of this analysis microsomal constituents have been classified, in the order of increasing median density, into four groups labeled a, b, c, and d. Group a includes: monoamine oxidase, galactosyltransferase, 5'-nucleotidase, alkaline phosphodiesterase I, alkaline phosphatase, and cholesterol; group b: NADH cytochrome c reductase, NADPH cytochrome c reductase, aminopyrine demethylase, cytochrome b₅, and cytochrome P 450; group c: glucose 6-phosphatase, nucleoside diphosphatase, esterase, ß-glucuronidase, and glucuronyltransferase; group d: RNA, membrane-bound ribosomes, and some enzymes probably adsorbed on ribosomes: fumarase, aldolase, and glutamine synthetase. Analysis of the microsomal fraction by differential centrifugation in density gradient has further dissociated group a into constituents which sediment more slowly (monoamine oxidase and galactosyltransferase) than those of groups b and c, and 5'-nucleotidase, alkaline phosphodiesterase I, alkaline phosphatase, and the bulk of cholesterol which sediment more rapidly (group a2). The microsomal monoamine oxidase is attributed, at least partially, to detached fragments of external mitochondrial membrane. Galactosyltransferase belongs to the Golgi complex. Group a2 constituents are related to plasma membranes. Constituents of groups b and c and RNA belong to microsomal vesicles derived from the endoplasmic reticulum. These latter exhibit a noticeable biochemical heterogeneity and represent at the most 80% of microsomal protein, the rest being accounted for by particles bearing the constituents of groups a and some contaminating mitochondria, lysosomes, and peroxisomes. Attention is called to the operational meaning of microsomal subfractions and to their cytological complexity.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

• Mora-Montes, H. M., Bader, O., Lopez-Romero, E., Zinker, S., Ponce-Noyola, P., Hube, B., Gow, N. A. R., Flores-Carreon, A. (2008). Kex2 protease converts the endoplasmic reticulum {alpha}1,2-mannosidase of Candida albicans into a soluble cytosolic form. Microbiology 154: 3782-3794 [Abstract] [Full Text]  
• Ruhl, R., Plum, C., Elmazar, M. M. A., Nau, H. (2001). Embryonic Subcellular Distribution of 13-cis- and All-trans-Retinoic Acid Indicates Differential Cytosolic/Nuclear Localization. Toxicol Sci 63: 82-89 [Abstract] [Full Text]  
• Lange, Y., Steck, T. L. (1997). Quantitation of the Pool of Cholesterol Associated with Acyl-CoA:Cholesterol Acyltransferase in Human Fibroblasts. J. Biol. Chem. 272: 13103-13108 [Abstract] [Full Text]  
• Brunner, C., Lobentanz, E.-M., Petho-Schramm, A., Ernst, A., Kang, C., Dieplinger, H., Muller, H.-J., Utermann, G. (1996). The Number of Identical Kringle IV Repeats in Apolipoprotein(a) Affects Its Processing and Secretion by HepG2 Cells. J. Biol. Chem. 271: 32403-32410 [Abstract] [Full Text]  
• Lavoie, C, Lanoix, J, Kan, F., Paiement, J (1996). Cell-free assembly of rough and smooth endoplasmic reticulum. J. Cell Sci. 109: 1415-1425 [Abstract]  

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents