Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
FEBS Lett. 2013 Jun 27;587(13):2028-35. doi: 10.1016/j.febslet.2013.05.015. Epub 2013 May 16.
Arf GTPases, together with Rab GTPases, are key regulators of intracellular membrane traffic. Their specific membrane targeting and activation are tightly regulated in time and space by guanine nucleotide exchange factors (GEFs). GEFs are multidomain proteins, which are under tight regulation to ensure fully coordinated and accurate membrane traffic events. Recently, two Arf GEFs, Sec7 and Arno, have been shown to be part of Arf GEF cascades similar to the Rab GEF cascades. Both GEFs are autoinhibited in solution and require an active Arf molecule to be recruited to the membrane and to switch to an open conformation. As such, positive feedback loops, whereby the amount of Arf-GTP on a given organelle increases not linearly with time, can be established.
Arf GTPases 与 Rab GTPases 一起，是细胞内膜运输的关键调节因子。它们的特定膜靶向和激活受到鸟嘌呤核苷酸交换因子 (GEF) 的严格时间和空间调节。GEFs 是多结构域蛋白，受到严格的调节以确保完全协调和准确的膜运输事件。最近，两种 Arf GEFs，Sec7 和 Arno，被证明是类似于 Rab GEF 级联的 Arf GEF 级联的一部分。这两种 GEF 在溶液中均自动抑制，需要活性 Arf 分子被招募到膜上并转换为开放构象。因此，可以建立正反馈环，即给定细胞器上的 Arf-GTP 量不会随时间线性增加。
