Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Six rat liver plasma-membrane subfractions of different density and morphological, enzymic and chemical properties were prepared from homogenates by a combination of differential, rate-zonal and density-gradient centrifugation. They consisted of three vesicular 'light' subfractions of density 1.12-1.13 and three 'heavy' subfractions of density 1.16-1.18 containing membrane strips and intercellular junctions. 2. All six subfractions contained a basal adenylate cyclase activity. One of the 'light' subfractions that showed the highest glucagon-stimulated adenylate cyclase activity was identified as deriving form the blood-sinusoidal face of the hepatocyte. This subfraction, unlike the others, was contaminated by Golgi components, as indicated by its morphological properties and the presence of galactosyl- and sialyl-transferase activities. 3. All the six subfractions showed high activities of the following plasma-membrane marker enzymes: 5'-nucleotidase, alkaline phosphodiesterase (nucleotide pyrophosphatase), alkaline phosphatase, leucine naphthylamidase and Mg2+-activated adenosine triphosphatase. A 'light' subfraction that showed the highest specific activities of all the above marker enzymes, but lacked a glucagon-stimulated adenylate cyclase activity, was identified as deriving from the bile-canalicular face of the hepatocyte. 4. The 'heavy' subfractions, which showed generally the lowest activities of the above plasma-membrane enzyme markers, and were characterized by the presence of desmosomes and gap junctions, were taken to originate from the contiguous faces of the hepatocyte. 5. The protein composition of the six subfractions was generally similar, as shown by polyacrylamide-gel electrophoresis. Differences in the amounts of various protein and glycoprotein bands among the subfractions correlated with their morphology, enzymic composition and sialic acid content. 6. Hormonal and histochemical evidence supporting the identification of a bile-canalicular subfraction, a blood-sinusoidal subfraction and contiguous-face subfractions is discussed.
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PMID:Functional polarity of the rat hepatocyte surface membrane. Isolation and characterization of plasma-membrane subfractions from the blood-sinusoidal, bile-Canalicular and contiguous surfaces of the hepatocyte. 12 84

Human Vgamma9Vdelta2 T lymphocytes are activated by phosphoantigens provided exogenously or produced by tumors and infected cells. Activation requires a contact between Vgamma9Vdelta2 cells and neighboring cells. We previously reported a role for cell surface F1-adenosine triphosphatase (ATPase) in T cell activation by tumors and specific interactions between Vgamma9Vdelta2 TCRs and purified F1-ATPase. 721.221 cells do not express surface F1-ATPase and do not support phosphoantigen responses unless they are rendered apoptotic by high doses of zoledronate, a treatment that promotes F1-expression as well as endogenous phosphoantigen production. By monitoring calcium flux in single cells, we show in this study that contact of T cells with F1-ATPase on polystyrene beads can partially replace the cell-cell contact stimulus during phosphoantigen responses. Triphosphoric acid 1-adenosin-5'-yl ester 3-(3-methylbut-3-enyl) ester, an adenylated derivative of isopentenyl pyrophosphate, can stably bind to F1-ATPase-coated beads and promotes TCR aggregation, lymphokine secretion, and activation of the cytolytic process provided that nucleotide pyrophosphatase activity is present. It also acts as an allosteric activator of F1-ATPase. In the absence of Vgamma9Vdelta2 cells, triphosphoric acid 1-adenosin-5'-yl ester 3-(3-methylbut-3-enyl) ester immobilized on F1-ATPase is protected from nucleotide pyrophosphatase activity, as is the antigenic activity of stimulatory target cells. Our experiments support the notion that Vgamma9Vdelta2 T cells are dedicated to the recognition of phosphoantigens on cell membranes in the form of nucleotide derivatives that can bind to F1-ATPase acting as a presentation molecule.
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PMID:F1-adenosine triphosphatase displays properties characteristic of an antigen presentation molecule for Vgamma9Vdelta2 T cells. 2048 57