Azhar S, Menon K M
Biochim Biophys Acta. 1975 May 5;392(1):64-74. doi: 10.1016/0304-4165(75)90166-x.
In a previous publication the purification and properties of two protein kinases (KI and KII) from a soluble fraction of bovine corpus luteum and the stimulation of the latter fol. Chem. 248,494-501). We have now studied the effects oc cyclic AMP and luteinizing hormone on ribosomal protein phosphorylation of corpus luteum by protein kinase II. Protein kinase II catalyzed the phosphorylation of ribosomes by transfer of terminal phosphate of ATP to ribosomal proteinsmextraction with hot trichloroacetic acid and non-aqueous solvent revealed that about 80% of total radioactivity incorporated remain associated with the protein residue. Radioactivity was identified in the phosphoserine and phosphothreonine residues of polypeptides by high voltage paper electrophoresis; The extent of phosphorylation was stimulated by cyclic AMP but not by luteinizing hormonemat least 9 proteins of 80-S ribosomes and 12 proteins of the 60-S ribosomal subunit were phosphorylated in the presence of cyclic AMP as resolved by urea polyacrylamide gel electrophoresis. However, only one major and four minor bands were phosphorylated in the ase of 40-S ribosomal subunit under the influence of cyclic AMP. The ribosomal protein phosphorylation catalyzed by protein kinase II is regulated by cyclic AMP wherease luteinizing hormone has no effect on ribosome phosphorylation.
在之前的一篇论文中，报道了从牛黄体的可溶部分纯化出两种蛋白激酶（KI和KII）及其性质，以及后者的刺激作用（《生物化学杂志》248,494 - 501页）。我们现在研究了环磷酸腺苷（cAMP）和促黄体生成素对蛋白激酶II催化的黄体核糖体蛋白磷酸化的影响。蛋白激酶II通过将ATP的末端磷酸基团转移到核糖体蛋白上，催化核糖体的磷酸化。用热三氯乙酸和非水溶剂提取后发现，掺入的总放射性中约80%仍与蛋白质残基结合。通过高压纸电泳在多肽的磷酸丝氨酸和磷酸苏氨酸残基中鉴定出放射性；磷酸化程度受cAMP刺激，但不受促黄体生成素刺激。如通过尿素聚丙烯酰胺凝胶电泳所解析，在cAMP存在下，80 - S核糖体的至少9种蛋白质和60 - S核糖体亚基的12种蛋白质发生了磷酸化。然而，在cAMP影响下，40 - S核糖体亚基只有一条主要带和四条次要带发生了磷酸化。蛋白激酶II催化的核糖体蛋白磷酸化受cAMP调节，而促黄体生成素对核糖体磷酸化没有影响。
