Matsumura S, Murakami N, Tashiro Y, Yasuda S, Kumon A
Arch Biochem Biophys. 1983 Nov;227(1):125-35. doi: 10.1016/0003-9861(83)90355-7.
A crude myosin fraction from bovine brain has been found to contain a Ca2+-independent myosin kinase that catalyzes the phosphorylation of 20,000-Da light chain of gizzard myosin. The myosin kinase has been separated from the myosin by Sepharose CL-4B gel filtration and purified further by chromatography on phosphocellulose, Sephacryl S-300, and hydroxylapatite. The myosin kinase was found to copurify with casein kinase II and show the same substrate specificity with the casein kinase. These results indicate that the myosin kinase is identical to casein kinase II. The purified myosin kinase catalyzed the preferential phosphorylation of the threonyl residues of 20,000-Da light chains of gizzard and brain myosins. The 17,000-Da light chains of these myosins and the mixed light chains of skeletal and cardiac muscle myosins were not phosphorylated by the enzyme to an appreciable extent.
已发现从牛脑提取的粗肌球蛋白组分含有一种不依赖Ca2+的肌球蛋白激酶，该激酶可催化砂囊肌球蛋白20,000道尔顿轻链的磷酸化。通过琼脂糖CL-4B凝胶过滤将肌球蛋白激酶与肌球蛋白分离，并进一步通过磷酸纤维素、Sephacryl S-300和羟基磷灰石层析进行纯化。发现该肌球蛋白激酶与酪蛋白激酶II共同纯化，并与酪蛋白激酶表现出相同的底物特异性。这些结果表明该肌球蛋白激酶与酪蛋白激酶II相同。纯化的肌球蛋白激酶催化砂囊和脑肌球蛋白20,000道尔顿轻链的苏氨酰残基优先磷酸化。这些肌球蛋白的17,000道尔顿轻链以及骨骼肌和心肌肌球蛋白的混合轻链未被该酶显著磷酸化。
