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Biomedical subjects

J T Buckley

Publications and source records attributed to J T Buckley.

97 records · Page 6Linked to original sources
PubMed1976

Synthesis of diphosphoinositide by a supernatant fraction from Acanthamoeba castellanii.

Homogenates of the free-living amoeba Acanthamoeba castellanii incorporate phosphate from [gamma-32P]ATP into a lipid which co-chromatographs with diphosphoinositide on one- and two dimensional chromatography. Incorporation into lipids similar in mobility to triphosphoinositide is not detected. The product co-chromatographs with diphosphoinositide whether exogenous phosphatidylinositol or total amoeba lipid is the substrate. The inositide kinase is almost entirely located in the supernatant fraction after centrifugation at 100 000 g. Incorporation of phosphate from [gamma-32P]ATP is linear for at least 15 min in the presence of 0.5 mM phosphatidylinositol. The enzyme requires Mg2+ of Mn2+ as well as ATP and it is not affected by low concentrations of Ca2+. The apparent Km for phosphatidylinositol in 2 mM. Both ADP and cAMP inhibit the reaction.

Amoeba↗
PubMed1974

Calcium ion transport by pig erythrocyte membrane vesicles.

Preincubating pig erythrocyte membranes with ATP enhances their ability to accumulate Ca(2+) against a concentration gradient. The extent of this increase is dependent on preincubation time over the period 0-60min. As the accessibility of outside membrane markers is decreased by preincubation and as accumulated Ca(2+) is not removed by EGTA [ethanedioxybis(ethylamine)tetra-acetate], it is suggested that ATP causes the formation of sealed inside-out vesicles which can transport Ca(2+) inward. The transport system requires ATP and Mg(2+) and exhibits an apparent dissociation constant for Ca(2+) of approx. 100mum. Since the dissociation constant for Ca(2+)-sensitive ATPase (adenosine triphosphatase) in these preparations is similar, it is concluded that this ATPase is responsible for Ca(2+) transport. Polyphosphoinositide concentrations are also increased during incubation with ATP; however, there is no change in their rate of synthesis or breakdown during Ca(2+) transport.

Adenosine Triphosphatases↗