Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The endoplasmic reticulum (ER) of MPC-11 cells released as vesicles upon cell disruption by nitrogen cavitation was separated from the bulk of mitochondria, lysosomes and plasma membranes by a low speed centrifugation. The ER membranes were fractionated on discontinuous sucrose gradients into heavy rough (HR), light rough (LR) and smooth (S) membranes. The morphology of subcellular fractions was studied by electron microscopy and the ER membranes were shown to be virtually free of contaminating organelles. The S fraction was easily distinguishable because of the lack or ribosomes but there were no apparent morphological differences between the HR and LR fractions. Of total activity in the microsomal subfractions, 70% of the UDPase and 67% of the 5'-nucleotidase activity was associated with the S fraction. Polysomes were present in the HR, LR and nuclear-associated ER fractions but not in the S fraction. The HR and LR fractions did not appear to be contaminated to any great extent with free polysomes. RNA/protein and RNA/phospholipid ratios of the HR fraction were higher than those of the LR fraction, indicating a greater density of ribosomes in the former fraction. These ratios were much lower in the S fraction reflecting the low ribosome content.
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PMID:Ultrastructure and polysome content of the microsomal subfractions of mouse plasmacytoma cells. 616 58

The fate of UDP formed during the galactosylation of added N-acetylglucosamine in Golgi vesicles isolated from rat liver using D2O-sucrose gradients has been determined. UDP-Gal labeled with [14C]uracil was used, and the products of the reaction were separated and quantitated by using high-pressure liquid chromatography. [14C]Uridine rather than [14C]UDP or [14C]UMP was found to accumulate, indicating the presence of both UDPase and UMPase activities in the Golgi. Golgi vesicles were shown to contain a nucleosidediphosphatase activity that is membrane bound. It appears to be located on the luminal face of the Golgi since it is activated 3-5-fold by detergents and 4-fold by treatment of the vesicles with Filipin. We have shown previously that Filipin disrupts the Golgi but does not solubilize membrane-bound enzymes. The nucleosidediphosphatase of the Golgi differs from that present in rough endoplasmic reticulum in its absolute requirement for Ca2+ for activity and in its substrate specificity that is higher for UDP than for IDP. Golgi vesicles also contain UMPase activity that is stimulated only 2-fold by detergents or Filipin. Concanavalin A inhibits this activity about 80% in both intact and detergent-treated vesicles. The Golgi UMPase is thus probably identical with 5'-nucleotidase. These results are consistent with histochemical evidence from other laboratories that indicate that 5'-nucleotidase is present on both sides of liver Golgi membranes. In the presence of concanavalin A and N-acetylglucosamine, intact Golgi vesicles were found to convert UDP-Gal to UMP. These findings indicate that UDP formed by galactosyltransferase in the lumen of the vesicles is rapidly converted to UMP by UDPase in the lumen but that UMP moves rapidly out of the lumen of the Golgi and is broken down to uridine by 5'-nucleotidase on the cytoplasmic side of the vesicles.
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PMID:Orientation and role of nucleosidediphosphatase and 5'-nucleotidase in Golgi vesicles from rat liver. 629 86