Purine and pyrimidine transport by cultured Novikoff cells. Specificities and mechanism of transport and relationship to phosphoribosylation.

Zylka, J M; Plagemann, Peter G.W.

doi:10.1016/s0021-9258(19)41119-8

Cited by 91 publications

(1 citation statement)

References 36 publications

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“…The alternate school believes that purine base transport, in some cell lines, is distinct from metabolism (Berlin & Hawkins, 1968;Berlin, 1970). Results from the studies of Zylka & Plagemann (1975) on Hyp/Gua phosphoribosyltransferase-deficient Novikoff cells supported the conclusion of the latter. Later, by using a rapid kinetic technique, Marz et al (1979) were able to measure the purine/pyrimidine influx into cells in which substrate conversion to nucleotides was negligible due either to lack of the appropriate enzymes or to depletion of cells of ATP (PRibPP).…”

Section: Discussionmentioning

confidence: 95%

Membrane-associated purine metabolizing enzyme activities of human peripheral blood cells

Yip¹,

Chang²,

Balis³

1982

Biochemistry

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Sealed and unsealed plasma membrane vesicles were prepared from human erythrocytes and lymphocytes. Phosphoribosylpyrophosphate synthetase (PRibPP synthetase), hypoxanthine phosphoribosyltransferase (HPRTase), and adenine phosphoribosyltransferase (APRTase) activities are detectable on both inside-out and right-side-out sealed vesicles. Ghost preparations were about 0.2%, 1%, and 1.2% of the total erythrocyte and 0.5%, 5.3%, and 9.7% of the lymphocyte APRTase, HPRTase, and PRibPP synthetase activities. The rapid decrease in these enzyme activities, upon further purification of the membranes, seemed to suggest that they might be loosely bound extrinsic proteins. Evidence confirming the localization of these enzymes on the cell surface was obtained by measuring production of [14C]AMP by intact cells in medium containing [14C]adenine, ribose 5-phosphate, and Mg2+ATP. The formation of AMP was linear with time and number of cells present. Magnesium and phosphate exerted different effects on the production of extracellular AMP than on intracellular, which involves transport as well as phosphoribosylation. Cytosoluble and membrane-bound APRTase and PRibPP synthetase exhibited different catalytic properties and sensitivities to effectors. Membranes of erythrocytes of HPRTase-deficient patients contain little or no HPRTase activity when assayed in the absence of Triton. Reisolation of these membranes from admixture with normal hemolysates did not result in any bound activity; thus, the membrane-bound activity is not an artifact of the isolation procedure. Lysis with Triton released activity equal to about half that of control membranes. This is further evidence that the enzyme is firmly bound to the membrane.

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Section: Discussionmentioning

confidence: 95%

Membrane-associated purine metabolizing enzyme activities of human peripheral blood cells

Yip¹,

Chang²,

Balis³

1982

Biochemistry

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Inherited Metabolic Disease: Prospects for the Future in Both Basic and Clinical Research

Watts

1977

Novartis Foundation Symposia

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Characteristics of taurine transport in rat hepatocytes in primary culture

Ohkuma¹,

Tamura²,

Kuriyama³

et al. 1984

Cell Biochemistry & Function

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Characteristics of taurine transport in rat hepatocytes maintained in primary culture for 24 h (cultured hepatocytes) have been investigated. The uptake of [3H] taurine by cultured hepatocytes at 2 degrees C was unsaturable, whereas that at 37 degrees C consisted of unsaturable and saturable processes. The saturable transport system was sodium-dependent and consisted of two processes with low and with high affinities. The latter process (Km, 76.9 microM; Vmax, 0.256 nmole/mg protein/min; activation energy (EA), 37.8 kcal mol-1) was competitively inhibited by 2,4-dinitrophenol and ouabain, as well as by taurine analogues such as hypotaurine and guanidinoethyl sulphonate. The Vmax and EA values found in cultured hepatocytes at 37 degrees C were 6.0 and 6.8 times higher than those found in freshly isolated hepatocytes. These results indicate that taurine transport in hepatocytes in primary culture consisted of unsaturable, and saturable, sodium and energy-dependent carrier-mediated transport processes, respectively. The facilitation of the latter transport system by primary culture of hepatocytes is also suggested.

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Purine and pyrimidine transport by cultured Novikoff cells. Specificities and mechanism of transport and relationship to phosphoribosylation.

Cited by 91 publications

References 36 publications

Membrane-associated purine metabolizing enzyme activities of human peripheral blood cells

Membrane-associated purine metabolizing enzyme activities of human peripheral blood cells

Inherited Metabolic Disease: Prospects for the Future in Both Basic and Clinical Research

Characteristics of taurine transport in rat hepatocytes in primary culture

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