Specificity of a protein phosphatase inhibitor from rabbit skeletal muscle.
Specificity of a protein phosphatase inhibitor from rabbit skeletal muscle.
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兔骨骼肌蛋白磷酸酶抑制剂的特异性。
DOI：
10.1042/bj1620435
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发表时间：
1977
期刊：
影响因子：
--
通讯作者：
J. Antoniw
中科院分区：
文献类型：
--
作者：
P. Cohen;G. Nimmo;J. Antoniw
一种心脏稳定的蛋白质，它是蛋白磷酸酶-III的特异性抑制剂，通过在95 ℃下热处理、在DEAE-纤维素上层析和在Sephadex G-100上凝胶过滤的程序从骨骼肌中纯化700倍。最后一步将蛋白磷酸酶抑制剂与环腺苷依赖性蛋白激酶的蛋白抑制剂完全分离。蛋白磷酸酶-III的磷酸化酶磷酸酶、β-磷酸化酶激酶磷酸酶、糖原合成酶磷酸酶-1和糖原合成酶磷酸酶-2活性[Antoniw，J.F.，尼姆，H. G.，Yeaman，S. J. & Cohen，P.（1977）Biochem.J. 162，423-433]以非常相似的方式被蛋白磷酸酶抑制剂抑制，并且在高浓度的抑制剂下观察到至少95%的抑制。蛋白磷酸酶III的两种形式，称为IIIA和IIIB，对蛋白磷酸酶抑制剂同样敏感。蛋白磷酸酶抑制剂在抑制蛋白磷酸酶-I和蛋白磷酸酶-II的活性方面的有效性至少低200倍。蛋白磷酸酶-III的抑制剂的高度特异性被用来表明，90%的磷酸化酶磷酸酶和糖原合成酶磷酸酶活性在肌肉提取物中测量的蛋白磷酸酶-III催化。蛋白磷酸酶-III与可以从骨骼肌中分离的蛋白-糖原复合物紧密相关，而蛋白磷酸酶抑制剂和蛋白磷酸酶-II则不相关。结果提供了进一步的证据，催化磷酸化酶激酶的α-亚基（蛋白磷酸酶-II）和催化磷酸化酶激酶的β-亚基（蛋白磷酸酶-III）的脱磷酸化的酶是不同的。结果表明，蛋白磷酸酶抑制剂可能是一个有用的探针，用于区分不同类型的蛋白磷酸酶在哺乳动物细胞。
A hear-stable protein, which is a specific inhibitor of protein phosphatase-III, was purified 700-fold from skeletal muscle by a procedure that involved heat-treatment at 95 degrees C, chromatography on DEAE-cellulose and gel filtration on Sephadex G-100. The final step completely resolved the protein phosphatase inhibitor from the protein inhibitor of cyclic AMP-dependent protein kinase. The phosphorylase phosphatase, beta-phosphorylase kinase phosphatase, glycogen synthase phosphatase-1 and glycogen synthase phosphatase-2 activities of protein phosphatase-III [Antoniw, J. F., Nimmo, H. G., Yeaman, S. J. & Cohen, P.(1977) Biochem.J. 162, 423-433] were inhibited in a very similar manner by the protein phosphatase inhibitor and at least 95% inhibition was observed at high concentrations of inhibitor. The two forms of protein phosphatase-III, termed IIIA and IIIB, were equally susceptible to the protein phosphatase inhibitor. The protein phosphatase inhibitor was at least 200 times less effective in inhibiting the activity of protein phosphatase-I and protein phosphatase-II. The high degree of specificity of the inhibitor for protein phosphatase-III was used to show that 90% of the phosphorylase phosphatase and glycogen synthase phosphatase activities measured in muscle extracts are catalysed by protein phosphatase-III. Protein phosphatase-III was tightly associated with the protein-glycogen complex that can be isolated from skeletal muscle, whereas the protein phosphatase inhibitor and protein phosphatase-II were not. The results provide further evidence that the enzyme that catalyses the dephosphorylation of the alpha-subunit of phosphorylase kinase (protein phosphatase-II) and the enzyme that catalyses the dephosphorylation of the beta-subunit of phosphorylase kinase (protein phosphatase-III) are distinct. The results suggest that the protein phosphatase inhibitor may be a useful probe for differentiating different classes of protein phosphatases in mammalian cells.