Polyphosphoinositide Breakdown without Calcium Mobilization: Studies with Adrenal Chromaffin Cells and Retina
The polyphosphoinositides (PtdIns4P and PtdIns(4, 5)P 2) have a considerable affinity for divalent cations and many years ago a physiological role in connection with calcium ions was suggested (Hawthorne and Kemp, 1964). In nervous tissue at least, the monoesterase and diesterase enzymes hydrolysing these lipids are much more active than the kinases responsible for their synthesis. The original description of PtdIns4P kinase by Kai et al. (1968) contains the following comment: “It (PtdIns(4, 5)P 2) resembles a transmitter substance in that the capacity for its destruction is very great”.
KeywordsHydrolysis Nicotine Retina Catecholamine Acetylcholine
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