Pathway for inositol 1,3,4-trisphosphate and 1,4-bisphosphate metabolism.
Pathway for inositol 1,3,4-trisphosphate and 1,4-bisphosphate metabolism.
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肌醇 1,3,4-三磷酸和 1,4-二磷酸代谢途径。
DOI：
10.1073/pnas.84.8.2170
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发表时间：
1987
影响因子：
11.1
通讯作者：
Majerus,PW
中科院分区：
文献类型：
--
作者：
Inhorn,RC;Bansal,VS;Majerus,PW
我们制备了[~ 3 H]肌醇-、3-[~（32）P]磷酸-和4-[~（32）P]磷酸-标记的肌醇磷酸底物，以研究肌醇1，3，4-三磷酸和肌醇1，4-二磷酸的代谢。在小牛脑的粗提物中，1，3，4-三磷酸肌醇首先转化为3，4-二磷酸肌醇，然后3，4-二磷酸肌醇中间体进一步转化为3-磷酸肌醇。类似地，肌醇1，4-二磷酸转化为肌醇4-磷酸，并且不形成肌醇1-磷酸。我们部分纯化的酶，我们暂时命名为肌醇多磷酸1-磷酸酶。这种胞质酶将肌醇1，3，4-三磷酸转化为肌醇3，4-二磷酸，也将肌醇1，4-二磷酸转化为肌醇4-磷酸。该酶不利用肌醇1，3，4，5-四磷酸、肌醇1，4，5-三磷酸或肌醇1-磷酸作为底物。因此，我们提出了一个新的计划肌醇磷酸代谢。根据该途径，肌醇1，4，5-三磷酸和肌醇1，4-二磷酸被降解为肌醇4-磷酸。肌醇1-磷酸是受刺激脑中形成的主要肌醇单磷酸，其来源于磷脂酶C裂解磷脂酰肌醇或肌醇环磷酸的降解。
We prepared [3H]inositol-,3-[32P]phosphate-and 4-[32P]phosphate-labeled inositol phosphate substrates to investigate the metabolism of inositol 1,3,4-trisphosphate and inositol 1,4-bisphosphate. In crude extracts of calf brain, inositol 1,3,4-trisphosphate is first converted to inositol 3,4-bisphosphate, then the inositol 3,4-bisphosphate intermediate is further converted to inositol 3-phosphate. Similarly, inositol 1,4-bisphosphate is converted to inositol 4-phosphate, and no inositol 1-phosphate is formed. We partially purified an enzyme that we tentatively name inositol polyphosphate 1-phosphatase. This cytosolic enzyme converts inositol 1,3,4-trisphosphate to inositol 3,4-bisphosphate and also converts inositol 1,4-bisphosphate to inositol 4-phosphate. The enzyme does not utilize inositol 1,3,4,5-tetrakisphosphate, inositol 1,4,5-trisphosphate, or inositol 1-phosphate as substrates. Thus we propose a new scheme for inositol phosphate metabolism. According to this pathway inositol 1,4,5-trisphosphate and inositol 1,4-bisphosphate are degraded to inositol 4-phosphate. Inositol 1-phosphate, which is the major inositol monophosphate formed in stimulated brain, is derived either from phospholipase C cleavage of phosphatidylinositol or from the degradation of inositol cyclic phosphates.