Kristiansen K, Plesner P, Krüger A
Eur J Biochem. 1978 Feb;83(2):395-403. doi: 10.1111/j.1432-1033.1978.tb12105.x.
Phosphorylation of ribosomal proteins in vivo was studied in exponentially growing and starved cells of the ciliated protozoan, Tetrahymena pyriformis. No phosphorylation of ribosomal proteins could be demonstrated in cells growing exponentially in complex nutrient media. However, when Tetrahymena cells were transferred into a non-nutrient medium, pronounced phosphorylation of a single ribosomal protein was observed. During two-dimensional polyacrylamide gel electrophoresis the phosphorylated ribosomal protein migrated in a manner virtually identical to that of the phosphorylated ribosomal protein S6 of rat liver. The phosphorylated ribosomal protein has a molecular weight of 38000 as estimated by dodecylsulfate polyacrylamide gel electrophoresis. Thus, the phosphorylated ribosomal protein found in starved Tetrahymena is apparently homologous with the ribosomal protein which is predominantly phosphorylated in higher eukaryotes. When phosphorylated ribosomes were dissociated by treatment with high concentration of KCl, the phosphorylated protein was found only on the small subunit. If dissociation was achieved by dialysis against a buffer low in MgCl2, the phosphorylated protein was distributed almost equally between the two subunits. This indicates that the phosphorylated ribosomal protein is located at the interface between the two subunits.
在纤毛原生动物梨形四膜虫指数生长和饥饿的细胞中研究了核糖体蛋白的体内磷酸化。在复杂营养培养基中指数生长的细胞中未检测到核糖体蛋白的磷酸化。然而，当梨形四膜虫细胞转移到无营养培养基中时，观察到单一核糖体蛋白发生明显磷酸化。在二维聚丙烯酰胺凝胶电泳过程中，磷酸化的核糖体蛋白迁移方式与大鼠肝脏磷酸化核糖体蛋白S6几乎相同。通过十二烷基硫酸钠聚丙烯酰胺凝胶电泳估计，该磷酸化核糖体蛋白的分子量为38000。因此，在饥饿的梨形四膜虫中发现的磷酸化核糖体蛋白显然与在高等真核生物中主要被磷酸化的核糖体蛋白同源。当用高浓度KCl处理使磷酸化核糖体解离时，磷酸化蛋白仅存在于小亚基上。如果通过对低MgCl2缓冲液进行透析来实现解离，磷酸化蛋白在两个亚基之间几乎平均分布。这表明磷酸化核糖体蛋白位于两个亚基之间的界面处。
