Max Planck Institute of Molecular Cell Biology and Genetics, Dresden D-01307, Germany.
Eur J Cell Biol. 2010 Aug;89(8):575-83. doi: 10.1016/j.ejcb.2010.02.004.
Sec7p, a guanine nucleotide exchange factor, regulates the activation of small Arf GTPases, which function in the formation of distinct classes of transport carriers from the Golgi. The recruitment of a subset of Arf effectors depends on the cooperation between these GTPases and phosphatidylinositol 4-phosphate. Here, we show that the catalytic domain of Sec7p interacts with a conserved region of the Golgi phosphatidylinositol 4-kinase Pik1p. We found that Sec7p and Pik1p as well as its product, colocalize at the late Golgi. Gea1p/Gea2p, an alternative pair of Arf activators, do not bind to Pik1p and function on a different Golgi sub-compartment. Sec7p and Pik1p interact with each other and cooperate in the formation of clathrin-coated vesicles. This interaction reveals a distinct role for Sec7p among the Golgi Arf-GEFs and provides a working model for the coordinated generation of Arf-GTP and phosphatiylinositol 4-phosphate as dual signal for specific recruitment of clathrin coats to the late Golgi.
Sec7p 是一种鸟嘌呤核苷酸交换因子，调节小 GTP 酶的激活，小 GTP 酶在高尔基体中形成不同类型的运输载体中发挥作用。一组特定的 Arf 效应因子的募集依赖于这些 GTP 酶和磷酸肌醇 4-磷酸之间的合作。在这里，我们表明 Sec7p 的催化结构域与 Golgi 磷脂酰肌醇 4-激酶 Pik1p 的保守区域相互作用。我们发现 Sec7p 和 Pik1p 及其产物在晚期高尔基体中共定位。Gea1p/Gea2p 是一对替代的 Arf 激活因子，不与 Pik1p 结合，作用于不同的高尔基体亚区室。Sec7p 和 Pik1p 相互作用，并在网格蛋白包被小泡的形成中合作。这种相互作用揭示了 Sec7p 在高尔基体 Arf-GEF 中的独特作用，并提供了一个工作模型，用于协调产生 Arf-GTP 和磷酸肌醇 4-磷酸作为双重信号，以特异性募集网格蛋白包被到晚期高尔基体。
