Tamura S, Kikuchi K, Kikuchi H, Hiraga A, Tsuiki S
Tohoku J Exp Med. 1980 Nov;132(3):341-8. doi: 10.1620/tjem.132.341.
When the crude phosphoprotein phosphatase fraction of rat liver cytosol was treated with 80% aqueous ethanol at room temperature, the activity with phosphorylase alpha as substrate was increased by 110%, but those with glycogen synthase D and phosphohistone were decreased by 53 and 34%, respectively. Chromatography of the ethanol-treated fraction on DE-52 revealed that while phosphoprotein phosphatase IA (Mr=69,000) remained to exist even though it was reduced, phosphatases IB (Mr=-300,00) and II (Mr=160,000) were totally replaced by a new phosphatase form with an approximate molecular weight of 35,000. This low molecular weight form has been designated phosphatase III. When partially purified phosphatases IB and II were separately treated with ethanol, they were converted to phosphatase III. These results suggest that phosphoprotein phosphatases IB and II, but IA, contain phosphatase III as a subunit. Phosphatases IB and II, however, must differ in structure since "IB to III" is accompanied by an increase in phosphorylase phosphatase activity much greater than that for "II to III"
当大鼠肝脏胞液中的粗制磷蛋白磷酸酶部分在室温下用80%的乙醇水溶液处理时，以磷酸化酶α为底物的活性增加了110%，但以糖原合酶D和磷酸化组蛋白为底物的活性分别降低了53%和34%。对经乙醇处理的部分在DE-52上进行色谱分析发现，尽管磷蛋白磷酸酶IA（分子量=69,000）有所减少但仍存在，而磷酸酶IB（分子量=-300,00）和II（分子量=160,000）完全被一种分子量约为35,000的新磷酸酶形式所取代。这种低分子量形式被命名为磷酸酶III。当将部分纯化的磷酸酶IB和II分别用乙醇处理时，它们会转化为磷酸酶III。这些结果表明，磷蛋白磷酸酶IB和II（而非IA）含有磷酸酶III作为亚基。然而，磷酸酶IB和II在结构上肯定有所不同，因为从“IB转化为III”时磷酸化酶磷酸酶活性的增加幅度远大于从“II转化为III”时的增加幅度。
