Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

K+-dependent, ouabain-sensitive nitrophenyl phosphatase (K+-NPPase) activity, which reflects the terminal dephosphorylation step of (Na+ + K+)-ATPase action, was studied histochemically in human thyroid normal follicular cells and in human thyroid carcinoma cells, using a newly developed one-step lead citrate method. In normal thyroid follicular cells, reaction product for K+-NPPase activity was found on the lateral plasma membrane and not on either the apical or basal plasma membrane. In thyroid carcinoma cells, a large amount of reaction product was observed on the lateral plasma membrane and also on the apical and basal plasma membrane. Appropriate control experiments indicated that the deposition of reaction product was K+ dependent and ouabain sensitive. Although there was some overlap in the distribution of reaction products for K+-NPPase and Mg2+-ATPase, significant differences were consistently observed. The biochemical findings indicated that the K+-NPPase activity per milligram of DNA in thyroid carcinoma cells was approximately 10 times higher than that in normal thyroid cells, and that a significant positive correlation exists between K+-NPPase and (Na+ + K+)-ATPase activity. The physiologic and pathologic implications of this localization for tracing the route of active Na+ transport, which might participate in the transport of iodide ion in both human thyroid normal follicular cells and human thyroid carcinoma cells, are discussed.
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PMID:Changes in localization of ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase activity in human thyroid carcinoma cells. 613 23

Synthetic alkylphospholipids (ALPs), such as edelfosine, miltefosine, perifosine, erucylphosphocholine and erufosine, represent a relatively new class of structurally related antitumor agents that act on cell membranes rather than on DNA. They selectively target proliferating (tumor) cells, inducing growth arrest and apoptosis, and are potent sensitizers of conventional chemo- and radiotherapy. ALPs easily insert in the outer leaflet of the plasma membrane and cross the membrane via an ATP-dependent CDC50a-containing 'flippase' complex (in carcinoma cells), or are internalized by lipid raft-dependent endocytosis (in lymphoma/leukemic cells). ALPs resist catabolic degradation, therefore accumulate in the cell and interfere with lipid-dependent survival signaling pathways, notably PI3K-Akt and Raf-Erk1/2, and de novo phospholipid biosynthesis. At the same time, stress pathways (e.g. stress-activated protein kinase/JNK) are activated to promote apoptosis. In many preclinical and clinical studies, perifosine was the most effective ALP, mainly because it inhibits Akt activity potently and consistently, also in vivo. This property is successfully exploited clinically in highly malignant tumors, such as multiple myeloma and neuroblastoma, in which a tyrosine kinase receptor/Akt pathway is amplified. In such cases, perifosine therapy is most effective in combination with conventional anticancer regimens or with rapamycin-type mTOR inhibitors, and may overcome resistance to these agents. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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PMID:Anticancer mechanisms and clinical application of alkylphospholipids. 2313 67