Rehmann Holger
Department of Physiological Chemistry, Centre for Biomedical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands.
Methods Enzymol. 2006;407:159-73. doi: 10.1016/S0076-6879(05)07014-X.
Epac1 and Epac2 are cAMP-dependent guanine nucleotide exchange factors (GEF) for the small G-proteins Rap1 and Rap2. Epac is inactive in the absence of cAMP, and binding of cAMP to a cyclic nucleotide-binding domain in the N-terminal regulatory region results in activation of the protein. The cAMP-dependent activity of Epac proteins can be analyzed by a fluorescence-based assay in vitro. These kinds of measurements can help to unravel the molecular mechanism by which cAMP binding is translated in activation of the protein. For this purpose, Epac mutants can be analyzed. In addition, the interaction of cAMP itself might be the focus of the research. Thus, modified cAMP analogs can be characterized by their ability to activate Epac. This is of particular interest for the development of Epac-specific analogs, which do not act on other cellular cAMP targets such as protein kinase A (PKA) or for the design of therapeutic agents targeting Epac.
Epac1和Epac2是小G蛋白Rap1和Rap2的环磷酸腺苷（cAMP）依赖性鸟嘌呤核苷酸交换因子（GEF）。在没有cAMP的情况下，Epac处于无活性状态，cAMP与N端调节区域中的环核苷酸结合结构域结合会导致该蛋白激活。Epac蛋白的cAMP依赖性活性可通过体外基于荧光的检测方法进行分析。这类测量有助于揭示cAMP结合转化为蛋白激活的分子机制。为此，可以分析Epac突变体。此外，cAMP自身的相互作用可能是研究的重点。因此，修饰的cAMP类似物可以通过其激活Epac的能力来表征。这对于开发不作用于其他细胞cAMP靶点（如蛋白激酶A，PKA）的Epac特异性类似物或设计靶向Epac的治疗药物尤为重要。
