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Characterization of inositol 1,3,4‐trisphosphate phosphorylation in rat liver
Author(s) -
Hansen Carl A.,
vom Dahl Stephan,
Huddell Benjamin,
Williamson John R.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80284-9
Subject(s) - inositol , inositol phosphate , phosphorylation , chemistry , biochemistry , inositol trisphosphate receptor , enzyme , vasopressin , inositol trisphosphate , receptor , biology , endocrinology
Liver homogenates phosphorylated Ins 1,3,4‐P 3 to an InsP 4 isomer that was distinct from Ins 1,3,4,5‐P 4 . This InsP 4 isomer accumulated in vasopressin stimulated hepatocytes prelabeled with myo‐ [ 3 H]inositol with a time course that lagged behind Ins 1,3,4‐P 3 formation. The Ins 1,3,4‐P 3 kinase responsible for its formation was partially purified from rat liver. The enzyme had a K m for Ins 1,3,4‐P 3 of 0.29 μM, a K m for ATP of 141 μM and was not affected by changes in free Ca 2+ in the physiological range. The relationship of this new InsP 4 isomer to the inositol phosphate signaling pathway is discussed.