The Purification and Characterization of Protein Phosphatase Inhibitor-1 from Rabbit Skeletal Muscle
The Purification and Characterization of Protein Phosphatase Inhibitor-1 from Rabbit Skeletal Muscle
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DOI：
10.1042/bst0060017
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发表时间：
1978-02-01
影响因子：
3.9
通讯作者：
Nimmo, Gillian A.
中科院分区：
文献类型：
--
作者：
Cohen, Philip;Nimmo, Gillian A.
哺乳动物骨骼肌中的糖原代谢受三种蛋白激酶和两种蛋白磷酸酶的磷酸化和去磷酸化反应控制。环amp依赖性蛋白激酶激活磷酸化酶激酶，灭活糖原合成酶[糖原（淀粉）合成酶]；2.4电子商务。1.1 11。然而，糖原合成酶也会被另一种称为糖原合成酶激酶2的酶灭活。糖原合成酶激酶2不使磷酸化酶激酶或磷酸化酶磷酸化，反之，磷酸化酶激酶激活磷酸化酶，但不使糖原合成酶磷酸化。磷酸化酶和磷酸化酶激酶的去磷酸化和失活（通过b亚基的去磷酸化）以及糖原合成酶的去磷酸化和再激活（由环amp依赖性蛋白激酶或糖原合成酶激酶2磷酸化）是由骨骼肌中的单一主要活性催化的，该活性被称为蛋白磷酸酶111。磷酸化酶激酶a-亚基的去磷酸化不直接影响活性，但将磷酸化酶激酶转化为蛋白磷酸酶111的较差底物形式，这是由一种称为蛋白磷酸酶- 1的独特酶催化的（Nimmo等人，1976；Antoniw等人）。, 1977;Cohen等人，1977a；Nimmo & Cohen, 1977)。蛋白磷酸酶I11的体外活性受到骨骼肌中存在的两种热稳定蛋白的抑制，称为抑制剂- 1和抑制剂-2 （Huang & Glinsmann, 1976）。抑制剂-1仅在被环amp依赖性蛋白激酶磷酸化后抑制蛋白磷酸酶- iii，而抑制剂-2的活性不受这种预孵育的影响（Huang & glinsnann, 1976）。本文描述了一种纯制剂抑制剂- 1的分离，介绍了其物理和化学性质，并考虑了其在糖原代谢激素控制中的潜在重要性。
Glycogen metabolism in mammalian skeletal muscle is controlled by phosphorylationdephosphorylation reactions that involve three protein kinases and two protein phosphatases. Cyclic AMP-dependent protein kinase activates phosphorylase kinase and inactivates glycogen synthetase [glycogen (starch) synthase; EC 2.4. 1.1 11. However, glycogen synthetase is also inactivated by a second enzyme termed glycogen synthetase kinase 2. Glycogen synthetase kinase 2 does not phosphorylate phosphorylase kinase or phosphorylase, and conversely, phosphorylase kinase activates phosphorylase, but does not phosphorylate glycogen synthetase. The dephosphorylation and inactivation of phosphorylase and phosphorylase kinase (through the dephosphorylation of the b-subunit) and the dephosphorylation and re-activation of glycogen synthetase (phosphorylated by either cyclic AMP-dependent protein kinase or by glycogen synthetase kinase 2) is catalysed by a single major activity in skeletal muscle, which has been termed protein phosphatase 111. The dephosphorylation of the a-subunit of phosphorylase kinase, which does not directly affect the activity, but converts phosphorylase kinase into a form that is a poorer substrate for protein phosphatase 111, is catalysed by a distinct enzyme, termed protein phosphatase-I1 (Nimmo et al., 1976; Antoniw et a/., 1977; Cohen er al., 1977a; Nimmo & Cohen, 1977). Protein phosphatase I11 activity in vitro is subject to inhibition by two heat-stable proteins that are present in skeletal muscle, termed inhibitor-I and inhibitor-2 (Huang & Glinsmann, 1976). Inhibitor-1 only inhibits protein phosphatase-III after it has been phosphorylated by the action of cyclic AMP-dependent protein kinase, whereas the activity of inhibitor-2 is unaffected by this preincubation (Huang & Glinsniann, 1976). In the present paper we describe the isolation of a pure preparation of inhibitor-I, present its physical and chemical properties and consider its potential importance in the hormonal control of glycogen metabolism.