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  • Title: Inhibitors of CDP-choline synthesis, action potential calcium channels, and stimulus-secretion coupling.
    Author: de Blas A, Adler M, Shih M, Chiang PK, Cantoni GL, Nirenberg M.
    Journal: Proc Natl Acad Sci U S A; 1984 Jul; 81(14):4353-7. PubMed ID: 6087319.
    Abstract:
    The effects of putative transmethylation inhibitors were tested on stimulus-secretion coupling and neurotransmitter secretion at synapses between neuroblastoma X glioma hybrid cells and myotubes. 5'-Deoxy-5'-isobutylthio-3-deazaadenosine or 5'-deoxy-5'-isobutylthioadenosine inhibited CDP-choline synthesis catalyzed by cholinephosphate cytidylyltransferase (CTP:cholinephosphate cytidylyltransferase, EC 2.7.7.15) and thereby decreased the rate of phosphatidylcholine synthesis from CDP-choline, but did not affect the transmethylation pathway for phosphatidylcholine synthesis. These compounds also inhibited 45Ca2+ uptake by hybrid cells mediated by voltage-sensitive Ca2+ channels, acetylcholine secretion at synapses, and signal transduction through cell membranes mediated by myotube nicotinic acetylcholine receptors. In contrast, 3-deazaadenosine or adenosine inhibited the transmethylation pathway for phosphatidylcholine synthesis, but had no effect on Ca2+ action potentials, acetylcholine secretion, or signal transduction through cell membranes mediated by nicotinic acetylcholine receptors. These results show that the stimulus-secretion coupling and secretion reactions studied are not dependent on phospholipid methylation and suggest that the activity of action potential Ca2+ channels and the rate of neurotransmitter secretion are functionally coupled to the rate of phosphatidylcholine synthesis via the CDP-choline pathway.
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