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Query: UNIPROT:Q00604 (X-linked)
 16,883 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of the c-erbB-2 oncoprotein (ErbB-2) and the nm23 anti-metastatic gene product (nucleoside diphosphate [NDP] kinase) was examined in the intraductal and invasive components of 63 fresh human breast cancer tissues. The expression of estrogen receptor (ER) as a marker of hormone dependency and the Ki-67 protein as a proliferative cell marker was also examined. ErbB-2 and ER were positive in 77.8% (28/36) and 64.7% (22/34) of the intraductal components, and in 43.6% (27/62) and 57.1% (36/63) of the invasive components, respectively. NDP kinase was positive in 58% (18/31) of intraductal, and in 30.9% (17/55) of invasive areas. The average Ki-67-positive cell rates were 5.9% in the intraductal, and 10.7% in the invasive components. Thus, the cells within the intraductal component of breast cancer appear to have different characteristics from the invasive component, not only in markers of proliferative ability, but also in the expression of oncogenes and hormone receptors.
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PMID:Estrogen receptor, c-erbB-2 and nm23/NDP kinase expression in the intraductal and invasive components of human breast cancers. 135 59

We have identified and partially purified a soluble nucleoside diphosphate kinase (NDP kinase) from Xenopus laevis oocytes. The enzyme preparation can catalyze the transfer of phosphate from ATP to all of the major oxy- and deoxynucleotides. It can also catalyze the transfer of a phosphorothioate group from gamma-S-ATP to an acceptor GDP forming gamma-S-GTP. Like NDP kinases from other sources, the catalytic mechanism appears to involve a phosphoenzyme intermediate which can be isolated. Transfer of phosphate from nucleoside triphosphates to protein is rapid, reaching saturation within 1 min following the addition of nucleoside triphosphates. The transfer of phosphate from phosphoprotein intermediate to nucleoside diphosphates is equally fast. While nucleoside diphosphate kinases are generally thought to require magnesium for activity, both the oocyte enzyme preparation and a commercial bovine liver enzyme preparation are only partially inhibited by short (10 min) exposures to 25 mM EDTA. Both enzyme preparations are, however, further inhibited by long incubations with this metal chelator (2 h, 70% inhibition). Zinc enhances the inhibition of NDP kinase by EDTA, but is ineffective on its own. Rapid phosphorylation in the presence of [gamma-32P]ATP and EDTA could be used to identify the phosphoenzyme intermediate in homogenates of Xenopus oocytes and facilitated its isolation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis coupled with autoradiography indicated the presence of only a single phosphorylated species of Mr 21,500 in supernatants of fresh oocyte homogenates. Partial purification of this protein utilizing salt precipitation, hydrophobic-interaction chromatography and an affinity step with Affi-Gel Blue Sepharose resulted in a 100-fold purification and a 29% overall yield of NDP-kinase activity. Size-exclusion chromatography of the purified preparation yielded two peaks containing enzyme activity. They eluted with apparent molecular weights of 45,000 and 70,000, suggesting a native enzyme that is multimeric or associated with other proteins.
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PMID:Nucleoside diphosphate kinase from Xenopus oocytes; partial purification and characterization. 217 46

Previous studies from this laboratory have proposed that membrane-associated nucleoside diphosphate kinase (m-NDP kinase) may play a role in regulation of adenylate cyclase by channeling GTP, an essential cofactor of adenylate cyclase regulation, into GTP-binding protein (Gs) in a hormone-dependent manner. To understand the true role of m-NDP kinase, in the present study, the m-NDP kinase was solubilized and purified to apparent homogeneity from rat liver purified plasma membranes and characterized in comparison with the cytosolic enzyme purified from the same tissue (s-NDP kinase). Some physical properties determined were: molecular weight (monomer), 18,300; sedimentation coefficient (s20,w), 6.2 S; isoelectric point (pI), 6.0. These values and kinetic parameters of the m-NDP kinase were almost identical to those of the s-NDP kinase whose characteristics were more extensively studied. A peptide mapping study of the 125I-labeled m- and s-NDP kinases gave essentially identical patterns. Polyclonal antibodies against the s-NDP kinase, which also cross-reacted with the m-NDP kinase, were prepared. Immunoblotting studies with the affinity-purified antibodies revealed that the monomer molecular weight of the purified m- and s-NDP kinases was identical to the values of unpurified enzymes present in membranes and crude extract. These results demonstrate that the purified m-NDP kinase underwent no remarkable modification during solubilization and purification, and that the m- and s-NDP kinases are quite similar in protein structure, if at all different. The physiological relevance of the m-NDP kinase in relation to the adenylate cyclase system is discussed.
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PMID:Membrane-associated nucleoside diphosphate kinase from rat liver. Purification, characterization, and comparison with cytosolic enzyme. 283 2

Recently, a DNA binding protein 'PUF' was purified that binds to a poly-pyrimidine rich element in the human c-myc promoter. Cloning of the corresponding gene surprisingly identified this putative transcription factor as isoform B of the enzyme nucleoside diphosphate kinase (NDPK-B) [Postel et al. (1993) Science, 261, 478-480], the product of the potential metastasis suppressor gene nm23-H2. Using different recombinant NDP kinases, we demonstrate by electrophoretic mobility shift analysis (EMSA) that the NDP kinase DNA binding properties are predominantly observed with human isoform B. Unlike typical DNA binding proteins that are involved in transcriptional regulation, binding occurs to single-stranded DNA rather than to a double-stranded oligonucleotide. As a consequence, complexes of single-stranded DNA and NDPK-B are generated from double-stranded oligonucleotide hybrids in an ATP independent manner. In addition to the c-myc element, NDPK-B is binding in vitro to a variety of poly-pyrimidine rich sequences including dC or dT homo-oligomers, (CT)n dinucleotide repeats, the initiator region of the Adenovirus major late promoter and even poly-pyrimidine rich RNAs. The possible consequences of these findings in understanding the multiple roles of NDP kinase are discussed.
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PMID:A human NDP-kinase B specifically binds single-stranded poly-pyrimidine sequences. 747 28

Soluble nucleoside-diphosphate kinase (NDP kinase) from Candida albicans was purified to electrophoretic homogeneity and a partial sequence was determined. The enzyme was kinetically and physically characterized. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme revealed a single polypeptide of 17 kDa upon staining, by immunodetection with heterologous and homologous antibodies, and by autoradiography of the phosphorylated enzyme. Furthermore, isoelectric focusing of the purified native enzyme showed a single acidic band (pI 4.5). These results together with a native molecular mass of 98 kDa suggest a hexameric native enzyme composed of identical subunits. Like NDP kinases from other sources, the catalysis involves a phosphoenzyme intermediate that is rapidly formed upon incubation of the enzyme with ATP. The transfer of phosphate from phosphoprotein intermediate to nucleoside diphosphates is equally fast. Kinetic experiments indicated that GTP and ATP had the lowest Km compared to UTP, dTTP, and CTP. GDP acted as a preferred acceptor as assessed by kinetic measurements as well as by competition experiments. Experimental data are presented indicating the existence of a membrane-associated NDP kinase. Preliminary characterization of this enzyme suggests that cytosolic and membrane-associated NDP kinases are similar proteins.
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PMID:Candida albicans nucleoside-diphosphate kinase: purification and characterization. 748 65

A soluble nucleoside diphosphate kinase (NDP kinase) was purified and characterized in epimastigote forms of Trypanosoma cruzi. The enzyme was purified by affinity chromatography on Blue-agarose and Q-Sepharose columns and by FPLC on a Superose 12 column. A membrane-associated NDP kinase was identified which accounts for 30% of total enzymatic activity. Western blot analysis of the soluble NDP kinase revealed a 16.5-kDa monomer recognized by polyclonal antibodies to NDP kinase from Dictyostelium discoideum, Candida albicans or human. Most of the T. cruzi NDP kinase is found in the cell as a hexamer composed of 16.5-kDa monomers. The Km values of the enzyme for ATP, GDP and dTDP were 0.2 +/- 0.008 mM, 0.125 +/- 0.012 mM and 0.4 +/- 0.009 mM, respectively. The parasite enzyme was stable, remained active at 65 degrees C and was found to tolerate up to 2.5 M urea. The 16.5-kDa subunit was phosphorylated with [gamma-32P]ATP or thiophosphorylated with [35S]GTP gamma S. The incubation of the 32P-labelled phosphoenzyme with unlabelled nucleoside 5'-diphosphates resulted in the formation of 32P-labelled nucleoside 5'-triphosphates without strict base specificity, indicating that the reaction mechanism of the T. cruzi enzyme is the same as reported for other NDP kinases. When the phosphoenzyme was incubated with a mixture of nucleoside 5'-diphosphates, GTP was preferentially formed.
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PMID:Purification and characterization of a soluble nucleoside diphosphate kinase in Trypanosoma cruzi. 763 92

A third type of nucleoside diphosphate kinase (NDP kinase III), distinct from the previously described NDP kinases I and II (Nomura et al. (1991) Biochim. Biophys. Acta 1077, 47-55), was purified from spinach leaves to electrophoretic homogeneity. NDP kinase III was judged by SDS-PAGE and by gel filtration to have molecular masses of 17 kDa and 102 kDa, respectively, suggesting that it is composed of six subunits similarly to the other spinach isoforms, NDP kinases I and II. Amino-acid sequence analysis revealed the primary structure of NDP kinase III to be comprised of 153 amino-acid residues, the sequence of which exhibited 61% and 53% homology with those of NDP kinases I and II, respectively. In the reaction catalyzed by the three isoforms, the order of Km as phosphate acceptor was determined as GDP << ADP for NDP kinase III, different from those observed for NDP kinase I (ADP << GDP) and for NDP kinase II (GDP = ADP). These results suggest that the three isoforms may have distinct roles in regulating intracellular 5'-di- and 5'-triphosphonucleotide levels in spinach leaves.
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PMID:A third type of nucleoside diphosphate kinase from spinach leaves: purification, characterization and amino-acid sequence. 771 Oct 53

Recently, several reports appeared which described auto-phosphorylation of NDP kinase on residues different from the active-site histidine. Based on these findings conclusions were drawn with respect to a regulation of enzyme activity and to a possible role as a metastasis suppressor. In this paper we show that although non-histidine autophosphorylation occurs on NDP kinases from mammals, lower eukaryotes and bacteria, less than 0.2% of the subunits are phosphorylated. Using site-directed mutagenesis, we show that the active site histidine is essential for non-histidine autophosphorylation. The low stoichiometry of phosphate incorporation excludes a role of autophosphorylation in regulating overall enzyme activity.
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PMID:Autophosphorylation of nucleoside diphosphate kinase on non-histidine residues. 792 21

The X-ray structure of the nucleoside diphosphate kinase (NDP kinase) from Dictyostelium discoideum has been refined at 1.8 A resolution from a hexagonal crystal form with a 17 kDa monomer in its asymmetric unit. The atomic model was derived from the previously determined structure of a point mutant of the protein. It contains 150 amino acid residues out of 155, and 95 solvent molecules. The R-factor is 0.196 and the estimated accuracy of the average atomic position, 0.25 A. The Dictyostelium structure is described in detail and compared to those of Drosophila and Myxococcus xanthus NDP kinases. The protein is a hexamer with D3 symmetry. Residues 8 to 138 of each subunit form a globular alpha/beta domain. The four-stranded beta-sheet is antiparallel; its topology is different from other phosphate transfer enzymes, and also from the HPr protein which, like NDP kinase, carries a phosphorylated histidine. The same topology is nevertheless found in several other proteins that bind mononucleotides, RNA or DNA. Strand connections in NDP kinase involve alpha-helices and a 20-residue segment called the Kpn loop. The beta-sheet is regular except for a beta-bulge in edge strand beta 2 and a gamma-turn at residue Ile120 just preceding strand beta 4. The latter may induce strain in the main chain near the active site His122. The alpha 1 beta 2 motif participates in forming dimers within the hexamer, helices alpha 1 and alpha 3, the Kpn loop and C terminus, in forming trimers. The subunit fold and dimer interactions found in Dictyostelium are conserved in other NDP kinases. Trimer interactions probably occur in all eukaryotic enzymes. They are absent in the bacterial Myxococcus xanthus enzyme which is a tetramer, even though the subunit structure is very similar. In Dictyostelium, contacts between Kpn loops near the 3-fold axis block access to a central cavity lined with polar residues and filled with well-defined solvent molecules. Biochemical data on point mutants highlight the contribution of the Kpn loop to protein stability. In Myxococcus, the Kpn loops are on the tetramer surface and their sequence is poorly conserved. Yet, their conformation is maintained and they make a similar contribution to the substrate binding site.
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PMID:Refined X-ray structure of Dictyostelium discoideum nucleoside diphosphate kinase at 1.8 A resolution. 796 7

The nucleoside diphosphate kinase (NDP kinase) from Myxococcus xanthus has been purified to homogeneity and crystallized (J. Munoz-Dorado, M. Inouye, and S. Inouye, J. Biol. Chem. 265:2702-2706, 1990). In the presence of ATP, the NDP kinase was autophosphorylated. Phosphoamino acid analysis was carried out after acid and base hydrolyses of phosphorylated NDP kinase. It was found that the protein was phosphorylated not only at a histidine residue but also at a serine residue. Replacement of histidine 117 with a glutamine residue completely abolished the autophosphorylation and nucleotide-binding activity of the NDP kinase. Since histidine 117 is the only histidine residue that is conserved in all known NDP kinases so far characterized, the results suggest that the phosphohistidine intermediate is formed at this residue during the transphosphorylation reaction from nucleoside triphosphates to nucleoside diphosphates. Preliminary mutational analysis of putative ATP-binding sites is also presented.
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PMID:Autophosphorylation of nucleoside diphosphate kinase from Myxococcus xanthus. 838 83


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