Bos J L
Laboratory for Physiological Chemistry and Center for Biomedical Genetics, Utrecht University, Universiteitsweg 100 3584 CG Utrecht, The Netherlands.
EMBO J. 1998 Dec 1;17(23):6776-82. doi: 10.1093/emboj/17.23.6776.
Ras, Rap1 and Ral are related small GTPases. While the function of Ras in signal transduction is well established, it has been recognized only recently that Rap1 and Ral also are activated rapidly in response to a large variety of extracellular signals. Between the three GTPase an intriguing interconnectivity exists, in that guanine nucleotide exchange factors for Ral associate with the GTP-bound form of both Ras and Rap1. Furthermore, Rap1 is considered to function as an antagonist of Ras signalling by trapping Ras effectors in an inactive complex. Here, I summarize the recent developments in understanding the functional relationship between these three GTPase and argue that Rap1 functions in a signalling pathway distinct from Ras, while using similar or identical effectors.
Ras、Rap1和Ral是相关的小GTP酶。虽然Ras在信号转导中的功能已得到充分证实，但直到最近人们才认识到，Rap1和Ral也会在多种细胞外信号的刺激下迅速被激活。这三种GTP酶之间存在着一种有趣的相互联系，因为Ral的鸟嘌呤核苷酸交换因子与Ras和Rap1的GTP结合形式相关联。此外，Rap1被认为通过将Ras效应器捕获在无活性复合物中而作为Ras信号传导的拮抗剂发挥作用。在此，我总结了在理解这三种GTP酶之间功能关系方面的最新进展，并认为Rap1在与Ras不同的信号通路中发挥作用，同时使用相似或相同的效应器。
