23 research outputs found

    Structure and Function of rap Proteins in Human Platelets

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    Stimulation by acetylcholine of phosphatidylinositol labelling. Subcellular distribution in rat cerebral-cortex slices

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    1. Rat cerebral-cortex slices were incubated with (32)P(i), acetylcholine and eserine for periods of 10min and 2h. The specific radioactivity of phosphatidylinositol was elevated during these treatments by 36 and 106% respectively. 2. The specific radioactivities of the phosphatidylinositol in different cell structures were determined after subcellular fractionation. They were highest in the nuclear, microsomal and synaptic-vesicle fractions and lowest in myelin, both in the controls and in the acetylcholine-treated slices. 3. The stimulated labelling of phosphatidylinositol was relatively evenly distributed: no subcellular fraction showed a stimulation markedly higher than that in the homogenate. 4. Studies of the distributions and activities of marker enzymes indicated that the subcellular fractionation achieved was similar to that with fresh tissue. 5. The results are discussed in relation to the previous report that the stimulation is observed throughout the neuronal cell-bodies and in relation to the hypothesis that the labelled phosphatidylinositol produced by stimulation is a component of an acetylcholine-receptor proteolipid localized in the synaptic junction

    Inositol 1:2-Cyclic Phosphate in Tissues

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    Preparation of 32P-labeled inositides and their degradation by soluble kidney enzymes

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    A method is described for the preparation of radioactive inositol lipids for studies of their enzymic degradation. Kidney cytosol fractions have been used to produce diesteratic cleavage. High voltage electrophoresis at pH 4.3 is used to separate -myoinositol 1: 2-cyclic phosphate and -myoinositol 1-phosphate from hydrolysis of phosphatidylinositol. Radioactivity co-migrating with myoinositol diphosphate and triphosphate is separated by electrophoresis at pH 1.5 following enzymatic hydrolysis of phosphatidylinositol phosphate and phosphatidylinositol diphosphate. Relative activities for hydrolysis of the various inositides suggest the presence of more than one phosphodiesterase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22022/1/0000438.pd
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