Satoh T, Endo M, Nakafuku M, Nakamura S, Kaziro Y
Institute of Medical Science, University of Tokyo, Japan.
Proc Natl Acad Sci U S A. 1990 Aug;87(15):5993-7. doi: 10.1073/pnas.87.15.5993.
The ras gene product (p21) is a GTP-binding protein and is thought to play an important role in signal transduction of growth and differentiation in many types of mammalian cells. The p21.GTP complex is an active conformation, as described previously for polypeptide chain elongation factors (EF-Tu and EF-G) and heterotrimeric GTP-binding proteins (G proteins). In the study reported here, we measured the amounts of p21-bound guanine nucleotides under various conditions in the G54 cell line, a derivative of Swiss 3T3 cells that overexpresses normal c-Ha-ras. More p21.GTP complexes were present in growing cells than in quiescent cells. When quiescent cells were stimulated with fetal bovine serum to promote DNA synthesis, p21.GTP increased approximately 2-fold. Among a number of purified growth factors, platelet-derived growth factor enhanced the formation of p21.GTP, whereas the combination of bombesin and insulin, which also induces DNA synthesis, did not. These results strongly suggest that p21 is a transducer of the growth signal from the platelet-derived growth factor receptor in Swiss 3T3 cells and that the signal is transmitted through a p21.GTP complex.
ras基因产物（p21）是一种GTP结合蛋白，被认为在多种哺乳动物细胞的生长和分化信号转导中起重要作用。如先前针对多肽链延伸因子（EF-Tu和EF-G）和异三聚体GTP结合蛋白（G蛋白）所描述的那样，p21.GTP复合物是一种活性构象。在本文报道的研究中，我们在G54细胞系（一种过表达正常c-Ha-ras的瑞士3T3细胞衍生物）的各种条件下测量了与p21结合的鸟嘌呤核苷酸的量。与静止细胞相比，生长细胞中存在更多的p21.GTP复合物。当用胎牛血清刺激静止细胞以促进DNA合成时，p21.GTP增加了约2倍。在许多纯化的生长因子中，血小板衍生生长因子增强了p21.GTP的形成，而同样诱导DNA合成的蛙皮素和胰岛素的组合则没有。这些结果强烈表明，p21是瑞士3T3细胞中来自血小板衍生生长因子受体的生长信号的转导器，并且该信号通过p21.GTP复合物进行传递。
