Weis J H, Faras A J
Biochemistry. 1983 Jan 4;22(1):165-70. doi: 10.1021/bi00270a024.
The two major phosvitin-utilizing kinases have been purified from virions of the Prague C strain of Rous sarcoma virus by the use of ion-exchange and affinity chromatography. The two kinases isolated may be differentiated by their molecular weights as well as by their ability to utilize GTP as a phosphate donor. Protein kinase G, which will use either GTP or ATP as a phosphate donor, has a molecular weight of 120 000 as determined under nondenaturing conditions by glycerol gradient centrifugation and 28 000 when assayed under denaturation in sodium dodecyl sulfate (Na-DodSO4)-polyacrylamide gels. Protein kinase A, which will only efficiently use ATP as the phosphate donor, has an apparent molecular weight of 43 000 estimated by glycerol gradient sedimentation and 40 000 by NaDodSO4-polyacrylamide electrophoresis. Both kinases possess the ability to autophosphorylate. Phosvitin is the major, and casein the minor, phosphate-accepting substrate for both kinases in vitro; however, kinase G will also phosphorylate histones to an extent similar to that observed with casein.
利用离子交换和亲和层析技术，从劳氏肉瘤病毒布拉格C株的病毒粒子中纯化出了两种主要的利用卵黄高磷蛋白的激酶。分离出的这两种激酶可通过分子量以及利用GTP作为磷酸供体的能力来区分。蛋白激酶G既可以使用GTP也可以使用ATP作为磷酸供体，在非变性条件下通过甘油梯度离心测定其分子量为120000，在十二烷基硫酸钠（Na-DodSO4）-聚丙烯酰胺凝胶中变性条件下测定时分子量为28000。蛋白激酶A仅能有效地使用ATP作为磷酸供体，通过甘油梯度沉降估计其表观分子量为43000，通过NaDodSO4-聚丙烯酰胺电泳测定为40000。两种激酶都具有自身磷酸化的能力。在体外，卵黄高磷蛋白是这两种激酶主要的磷酸接受底物，酪蛋白是次要的；然而，激酶G也能使组蛋白磷酸化，其程度与酪蛋白相似。
