Preparation and properties of plasma membrane and endoplasmic reticulum fragments from isolated rat fat cells
Avruch, J.; Wallach, D.F.
Biochimica et Biophysica Acta 233(2): 334-347
1971
ISSN/ISBN: 0006-3002 PMID: 4326970 DOI: 10.1016/0005-2736(71)90331-2
Accession: 027193223
1.1. Plasma membrane and endoplasmic reticulum of free fat cells were isolated in high yield as a mixed microsomal fraction by sucrose gradient centrifugation.2.2. The semipermeable behavior of these particles was explored by observing shifts in isopycnic density in continuous polymer (Dextran) gradients over a range of pH and ionic conditions.3.3. Using a discontinuous Dextran gradient, a plasma membrane fraction was partially purified. The plasma membrane fraction showed a 12–16-fold enrichment of 5-nucleotidase over the homogenate. Na+-K+-stimulated ATPase was recovered in highest specific activity in this fraction. Mitochondrial contamination was 3% where endoplasmic reticulum contamination was 27%.4.4. A sensitive radioassay for 5-nucleotidase is described.