Andres J L, Johansen J W, Maller J L
Department of Pharmacology, University of Colorado School of Medicine, Denver 80262.
J Biol Chem. 1987 Oct 25;262(30):14389-93.
Protein phosphatases 1 and 2B from rabbit skeletal muscle were found to catalyze the dephosphorylation of ribosomal protein S6 in vitro. Phosphorylation of protein phosphatase-1 by the transforming protein of Rous sarcoma virus, pp60v-src, abolished S6 dephosphorylation by the purified enzyme. Analysis of the dephosphorylation of phosphorylase a and phosphorylase kinase in Xenopus oocyte extracts and after microinjection indicated the presence of oocyte enzymes similar to protein phosphatases-1 and -2B. Studies with 32P-labeled 40 S ribosomal subunits suggested that these enzymes were functioning as S6 phosphatases in oocytes. These findings support the hypothesis that regulation of protein phosphatase activity may be involved in the increase in S6 phosphorylation observed after mitogenic stimulation.
已发现来自兔骨骼肌的蛋白磷酸酶1和2B在体外催化核糖体蛋白S6的去磷酸化。劳斯肉瘤病毒的转化蛋白pp60v-src对蛋白磷酸酶-1的磷酸化作用，使纯化酶对S6的去磷酸化作用丧失。对非洲爪蟾卵母细胞提取物及显微注射后的磷酸化酶a和磷酸化酶激酶的去磷酸化分析表明，存在类似于蛋白磷酸酶-1和-2B的卵母细胞酶。对32P标记的40S核糖体亚基的研究表明，这些酶在卵母细胞中作为S6磷酸酶发挥作用。这些发现支持了这样一种假说，即蛋白磷酸酶活性的调节可能参与有丝分裂原刺激后观察到的S6磷酸化增加。
