Bole of protein targeting to glycogen (PTG) in the regulation of protein phosphatase-1 activity
Bole of protein targeting to glycogen (PTG) in the regulation of protein phosphatase-1 activity
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DOI：
10.1074/jbc.272.32.20198
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发表时间：
1997-08-08
影响因子：
4.8
通讯作者：
Saltiel, AR
中科院分区：
文献类型：
--
作者：
Brady, MJ;Printen, JA;Saltiel, AR
我们最近从3T3-L1脂肪细胞中克隆了一个新的糖原标记的蛋白磷酸酶-1亚单位，称为PTG(print ten，5，A.，Brady，M.J.，and Saltiel，A.R.(1997)Science 2751475-1478)，将3T3-L1成纤维细胞分化为高胰岛素反应性脂肪细胞，导致显著增加：在PTG表达中，固定化谷胱甘肽S转移酶-PTG融合蛋白特异性地结合PP1或磷酸化酶a。PTG的裂解产物通过将PP1的K-m降低5倍来增加PP1的活性以对抗P-32标记的磷酸化酶a，同时对去磷酸化反应的V-max有很大的影响，或者，PTG并不影响PP1对抗激素敏感的脂肪酶的活性，PTG不是细胞内信号转导的直接靶点，因为胰岛素或Forsklin处理细胞并不激活能够在体内或体外磷酸化PTG的激酶，最后，PTG降低了DARPP-32抑制3T3-L1脂肪细胞裂解物中PP1活性的能力，这些数据累积表明PTG通过几种不同的机制增加了针对特定蛋白质的PPI活性。
We have recently cloned from 3T3-L1 adipocytes a novel glycogen-tageting subunit of protein phosphatase-1, termed PTG (Printen, 5, A., Brady, M. J., and Saltiel, A. R. (1997) Science 275, 1475-1478), Differentiation of 3T3-L1 fibroblasts into highly insulin-responsive adipocytes resulted in a marked increase: in PTG expression, Immobilized glutathione S-transferase (GST)-PTG fusion protein specifically bound either PP1 or phosphorylase a, Addition of soluble GST-PTG to 3T3-L1. lysates increased PP1 activity against P-32-labeled phosphorylase a by decreasing the K-m of PP1 for phosphorylase 5-fold, while having ma effect on the V-max, of the dephosphorylation reaction, Alternatively, PTG did not affect PP1 activity against hormone-sensitive lipase, PTG was not a direct target of intracellular signaling, as insulin or forskolin treatment of cells did not activate a kinase capable of phosphorylating PTG in vivo or irt vitro, Finally, PTG decreased the ability of DARPP-32 to inhibit PP1 activity from 3T3-L1 adipocyte lysates, These data cumulatively suggest that PTG increases PPI activity against specific proteins by several distinct mechanisms.