Stepwise enzymatic dephosphorylation of inositol 1,4,5-trisphosphate to inositol in liver

Many receptors for hormones, neurotransmitters and other signals cause hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P 2 ) and effect a rise in cytosolic Ca 2+ concentration 1–7 . The inositol 1,4,5-trisphosphate (Ins(1,4,5)P 3 ) liberated during PtdIns(4,5)P 2 breakdown seems to s...

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Bibliographic Details
Published in:Nature (London) 1984-01, Vol.312 (5992), p.374-376
Main Authors: Storey, Diane J., Shears, Stephen B., Kirk, Christopher J., Michell, Robert H.
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Cadmium - pharmacology
Cell Membrane - enzymology
Cell physiology
Cytoplasm - enzymology
dephosphorylation
Fundamental and applied biological sciences. Psychology
Humanities and Social Sciences
Inositol - metabolism
Inositol Phosphates - metabolism
Inositol Polyphosphate 5-Phosphatases
inositol-1,4,5-triphosphate
Kinetics
letter
liver
Liver - metabolism
Molecular and cellular biology
multidisciplinary
Phosphoric Monoester Hydrolases - antagonists & inhibitors
Phosphoric Monoester Hydrolases - metabolism
Rats
Responses to growth factors, tumor promotors, other factors
Science
Science (multidisciplinary)
Subcellular Fractions - enzymology
Sugar Phosphates - metabolism
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Summary:Many receptors for hormones, neurotransmitters and other signals cause hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P 2 ) and effect a rise in cytosolic Ca 2+ concentration 1–7 . The inositol 1,4,5-trisphosphate (Ins(1,4,5)P 3 ) liberated during PtdIns(4,5)P 2 breakdown seems to serve as a second messenger that activates the release of Ca 2+ from a nonmitochondrial intracellular compartment 7–12 . As expected if it is an important intracellular messenger, Ins(1,4,5)P 3 is relatively rapidly degraded, both within stimulated cells 13,14 and when added to homogenates of blowfly salivary gland 15 or to permeabilized, but not intact, hepatocytes 10 . Here we report that the dephosphorylation reactions responsible for the conversion of Ins(1,4,5)P 3 to free inositol in rat liver are catalysed by two or more enzymes, and that these reactions are distributed between the plasma membrane and cytosol. The Ins(1,4,5)P 3 5-phosphatase and inositol 1-phosphate (Ins(1)P) phosphatase of liver appear similar to enzymes described previously in erythrocytes 16 and brain 17 .
ISSN:0028-0836
1476-4687
DOI:10.1038/312374a0