Martin-Pérez J, Thomas G
Proc Natl Acad Sci U S A. 1983 Feb;80(4):926-30. doi: 10.1073/pnas.80.4.926.
The amino acids and tryptic peptides that become phosphorylated in 40S ribosomal protein S6 after serum stimulation of quiescent 3T3 cells were examined by two-dimensional thin-layer electrophoresis. In the maximally phosphorylated form of the protein, most of the phosphate was incorporated into serine and a small amount, into threonine. Digestion of this form of the protein with trypsin revealed 10 major phosphopeptides. All 10 contained phosphoserine and 2 of the 10 also contained phosphothreonine. Next, the five forms of increasingly phosphorylated S6 were individually separated on two-dimensional polyacrylamide gels or total S6 was isolated from cells that were stimulated for only a short time and their phosphotryptic maps were analyzed. The results showed that, as larger amounts of phosphate were added to S6, the phosphopeptides appeared in a specific order.
通过二维薄层电泳检测了静止的3T3细胞在血清刺激后40S核糖体蛋白S6中发生磷酸化的氨基酸和胰蛋白酶肽段。在该蛋白的最大磷酸化形式中，大部分磷酸基团掺入丝氨酸，少量掺入苏氨酸。用胰蛋白酶消化这种形式的蛋白后，发现了10个主要的磷酸肽段。所有10个都含有磷酸丝氨酸，其中2个还含有磷酸苏氨酸。接下来，在二维聚丙烯酰胺凝胶上分别分离了S6的五种磷酸化程度逐渐增加的形式，或者从仅短期刺激的细胞中分离出总S6，并分析其磷酸化胰蛋白酶图谱。结果表明，随着越来越多的磷酸基团添加到S6中，磷酸肽段按特定顺序出现。
