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)

Homogenisation and fractionation of cells in the presence of Mg2+ or EDTA resulted in unoccupied oestrogen receptor being recovered in the particulate fraction. Nuclei were partially purified by pelleting at 100,000 g through 41% and 44% (w/w) sucrose (in buffer containing Mg2+ or EDTA), plasma membranes being collected from the top of the 41% barrier. In Mg2+-prepared fractions, both 5'-nucleotidase and unoccupied receptor were distributed between plasma membrane, partially-pure nuclei and mitochondrial/microsomal pellets. Lactate dehydrogenase was not a significant contaminant of particulate fractions. In EDTA fractions, the majority of binding activity was in the partially-pure nuclei (which were extensively disrupted) and mitochondrial/microsomal pellets. Little or no binding was found in the EDTA-prepared plasma membranes which were amorphous in appearance. Mg2+-prepared nuclei, freed of membranous contamination by pelleting through 1.8 M sucrose, were intact by electron microscopy but had no 5'-nucleotidase or unoccupied receptor. These data suggest that recovery of receptor in partially-pure nuclei during fractionation is not caused by trapping of cytosolic protein but rather by redistributed nuclear receptor having become bound to adhering plasma membrane fragments during homogenisation. Implications for the study of cell-free systems are discussed.
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PMID:The effects of Mg2+ ions or EDTA on nuclear integrity and apparent subcellular distribution of unoccupied oestrogen receptors in breast cancer cells. 309 86

More than half of the extranuclear receptor content of resting cells is associated with cytoplasmic structures. Subfractionation of microsomes reveals a preponderance of "basic" (low electrophoretic mobility) receptor in rough endoplasmic reticulum. Surfynol-dithiothreitol extracts of smooth membranes are rich in "acidic" (high electrophoretic mobility) receptor. Trypsin increases the yields up to seven-fold, and this increase is correlated (r = 0.993) with the acidic receptor content and 5'-nucleotidase activity of these microsomal preparations. Acidic microsomal "cytosolic" and nuclear receptor can be degraded to the "basic" variety of streptomyces hyaluronidase. All forms give rise to a tryptic fragment with unchanged affinity for oestradiol and dimerization ability. Basic receptor isolated after enzymatic conversion of acidic receptor is microheterogenous on isoelectric focusing, but gives rise to only one precipitation arc versus the IgG fraction of a polyclonal antiserum. The precipitation arc can be recharged with labelled oestradiol and autoradiographed. Non-immune IgG's from (unspecific) soluble complexes with oestrogen receptors, but not with their tryptic fragments. The polyclonal antioestrogen receptor IgG fraction precipitates the oestradiol-tagged tryptic receptor fragment from all subcellular sources of all homologous (porcine) and heterologous (human, ovine, bovine, goat, rabbit, guinea pig, rat) target tissues tested. Organ specificity can therefore be excluded and a high degree of phylogenetic conservation of the oestrogen receptor's protein moiety is implied. The presence, in the immune IgG fraction, of steroid releasing antibodies, which apparently distort the binding site, should spur the search for monoclonal antibodies with similar properties.
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PMID:Subcellular distribution, properties and interrelationship of oestrogen receptors in endometrium and other target tissues. 663 34