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At least 811 records · Page 45Linked to original sources
PubMed1980

Isolation of rat brain subcellular fraction enriched in putative neurotransmitter receptors and synaptic junctions.

A simple reliable method was developed for the rapid isolation of a synaptic plasma membrane-enriched fraction from rat brain. The procedure involves the direct lysis of a crude mitochondrial fraction followed by a combined flotation-sedimentation density gradient centrifugation in a fixed-angle centrifuge rotor. All fractions have been characterized with respect to relative enrichment of (Na+-K+)ATPase activity as well as putative cholinergic neurotransmitter receptors determined by [125I]alpha-bungarotoxin and [3H]quinuclidinyl benzilate binding. The 2- to 4-fold relative enrichment of putative receptor binding sites correlated well with the 4-fold enrichment of morphologically identifiable synaptic junctions in the synaptic plasma membrane enriched fraction.

Animals↗
PubMed2004

Detailed analytical subcellular fractionation of non-pregnant porcine corpus luteum reveals peroxisomes of normal size and significant UDP-glucuronosyltransferase activity in the high-speed supernatant.

A detailed subfractionation of the non-pregnant porcine corpus luteum (CL) was performed employing differential centrifugation. Marker enzyme assays (i.e., lactate dehydrogenase for the cytosol, NADPH-cytochrome P450 reductase for the endoplasmatic reticulum, catalase (CAT) for peroxisomes, glutamate dehydrogenase for the mitochondrial matrix and acid phosphatase for lysosomes) in all subfractions obtained exhibited a pattern of distribution similar to that observed with rat liver. These subfractions should be useful in connection with many types of future studies. In disagreement with previous biochemical and morphological studies, peroxisomes (identified on the basis of catalase activity and by Western blotting of catalase and of the major peroxisomal membrane protein (PMP-70)) sedimented together with mitochondria (i.e., at 5000 x g(av) for 10 min) and not in the post-mitochondrial fraction prepared at 30,000 x g(av) for 20 min by Peterson and Stevensson. No other classical peroxisomal enzymes were detectable in the porcine ovary, raising questions concerning the function of peroxisomes in this organ. Furthermore, UDP-glucuronosyltransferase (UGT), generally considered to be an integral membrane protein anchored in the endoplasmatic reticulum, was recovered in both the cytosolic (i.e., the supernatant after centrifugation at 50,000 x g(av) for 1h) and the microsomal fraction of the porcine corpus luteum, even upon further centrifugation of the former. In contrast, UGT sediments exclusively in the microsomal fraction upon subfractionation of the liver and ovary from rat.

Animals↗
PubMed1966

Studies of lung metabolism. I. Isolation and properties of subcellular fractions from rabbit lung.

The isolation and partial characterization of subcellular particles from rabbit and rat lung are described. Detailed methods for separating a purified, active mitochondrial fraction are outlined and evaluated in terms of enzymatic, chemical, and morphological criteria. Mitochondrial preparations from rabbit and rat liver were used as comparative indices. The lung mitochondrial fraction was identified by its ability to oxidize succinate with a P/O ratio of 1.7 by a process sensitive to 2,4 dinitrophenol and antimycin A. The adenosine triphosphatase activity of the lung mitochondrial fraction is stimulated by magnesium ions, but this stimulation is not augmented by 2,4 dinitrophenol. In the absence of magnesium ions, the specific activity of the adenosine triphosphatase increases with increasing protein concentration. The presence of lysosomes in the mitochondrial fraction is suggested by acid phosphatase and cathepsin activities and by electron microscope observations.

Acid Phosphatase↗
PubMed2003

Inhibition of the neutrophil NADPH oxidase by adenosine is associated with increased movement of flavocytochrome b between subcellular fractions.

Adenosine is a potent inhibitor of reactive oxygen species (ROS) production by the NADPH oxidase in fMLF-stimulated neutrophils. Although much is known about the pharamacology and signal transduction of this effect, it is not known how adenosine affects assembly and localization of the NADPH oxidase components within the neutrophil. We report here that adenosine pretreatment of fMLF-stimulated neutrophils results in decreased plasma membrane/secretory granule content of the flavocytochrome b components (p22phox and gp91phox) of the NADPH oxidase, which correlates with inhibition of ROS production. Adenosine treatment did not affect upregulation of secretory and specific granule surface markers, confirming that degranulation was not impaired by adenosine. However, adenosine treatment did result in increased movement of cell-surface flavocytochrome b to heavy granule fractions in fMLF-stimulated neutrophils. These data suggest that adenosine-mediated effects on neutrophil ROS production are due, in part to endocytosis and/or redistribution of flavocytochrome b between various subcellular compartments.

Adenosine↗