A PROTEIN-KINASE FROM XENOPUS EGGS SPECIFIC FOR RIBOSOMAL-PROTEIN S6
A PROTEIN-KINASE FROM XENOPUS EGGS SPECIFIC FOR RIBOSOMAL-PROTEIN S6
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DOI：
10.1073/pnas.82.3.742
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发表时间：
1985-01-01
影响因子：
11.1
通讯作者：
MALLER, JL
中科院分区：
文献类型：
--
作者：
ERIKSON, E;MALLER, JL
从黄脊灰蝶卵中纯化了一种核糖体蛋白S6特异性蛋白激酶。光滑。如在Ag染色的聚丙烯酰胺凝胶上可见的，制备物中的主要蛋白质以90，000的MW迁移。将酶制剂与[γ- [32 P]ATP导致该蛋白在丝氨酸残基上磷酸化。甘油梯度离心后，S6激酶活性和MW 90，000蛋白质均以50，000 - 55，000的MW沉降。二维凝胶电泳表明，多达4-5个磷酸基团，每个S6分子可以与这种酶在体外，和二维肽图谱表明，磷酸肽从S6标记在体外与酶comigrated与那些高度磷酸化的S6标记在体内响应孕酮治疗。纯化的S6蛋白激酶没有磷酸化在一个显着的速率核糖体蛋白S10，组蛋白H1，组蛋白H4，混合组蛋白，酪蛋白，或卵黄蛋白，表明底物的高度特异性。单个S6蛋白激酶的激活可能足以解释生长刺激后S6磷酸化的增加。
A protein kinase specific for ribosomal protein S6 was purified from eggs of X. laevis. As visualized on a Ag-stained polyacrylamide gel, the major protein in the preparation migrated with a MW of 90,000. Incubation of the enzyme preparation with [.gamma.-32P]ATP led to phosphorylation of this protein on Ser resudies. Upon glycerol gradient centrifugation, the S6 kinase activity and the MW 90,000 protein both sedimented with a MW of 50,000-55,000. Two-dimensional gel electrophoresis demonstrated that up to 4-5 phosphate groups per S6 molecule could be incorporated with this enzyme in vitro, and 2-dimensional peptide mapping demonstrated that the phosphopeptides from S6 labeled in vitro with the enzyme comigrated with those from highly phosphorylated S6 labeled in vivo in response to progesterone treatment. The purified S6 protein kinase did not phosphorylate at a significant rate ribosomal protein S10, histone H1, histone H4, mixed histones, casein, or phosvitin, indicating a high degree of substrate specificity. Activation of a single S6 protein kinase may be sufficient to account for increased S6 phosphorylation after a growth stimulus.