Department of Internal Medicine I, University of Ulm, Ulm 89081, Germany.
Mol Biol Cell. 2010 Mar 15;21(6):1011-22. doi: 10.1091/mbc.e09-09-0814. Epub 2010 Jan 20.
Protein kinase D (PKD) isoenzymes regulate the formation of transport carriers from the trans-Golgi network (TGN) that are en route to the plasma membrane. The PKD C1a domain is required for the localization of PKDs at the TGN. However, the precise mechanism of how PKDs are recruited to the TGN is still elusive. Here, we report that ADP-ribosylation factor (ARF1), a small GTPase of the Ras superfamily and a key regulator of secretory traffic, specifically interacts with PKD isoenzymes. ARF1, but not ARF6, binds directly to the second cysteine-rich domain (C1b) of PKD2, and precisely to Pro275 within this domain. Pro275 in PKD2 is not only crucial for the PKD2-ARF1 interaction but also for PKD2 recruitment to and PKD2 function at the TGN, namely, protein transport to the plasma membrane. Our data suggest a novel model in which ARF1 recruits PKD2 to the TGN by binding to Pro275 in its C1b domain followed by anchoring of PKD2 in the TGN membranes via binding of its C1a domain to diacylglycerol. Both processes are critical for PKD2-mediated protein transport.
蛋白激酶 D（PKD）同工酶调节从跨高尔基网络（TGN）形成运输载体，这些载体正在前往质膜的途中。PKD C1a 结构域是 PKD 定位于 TGN 的必需条件。然而，PKD 如何被招募到 TGN 的精确机制仍然难以捉摸。在这里，我们报告说，ADP-核糖基化因子（ARF1），一种 Ras 超家族的小 GTPase，是分泌流量的关键调节剂，与 PKD 同工酶特异性相互作用。ARF1 但不是 ARF6，直接与 PKD2 的第二个富含半胱氨酸的结构域（C1b）结合，并且精确地结合到该结构域内的 Pro275。PKD2 中的 Pro275 不仅对 PKD2-ARF1 相互作用至关重要，而且对 PKD2 在 TGN 的募集和 PKD2 在 TGN 的功能也至关重要，即蛋白质向质膜的运输。我们的数据表明了一个新的模型，其中 ARF1 通过结合其 C1b 结构域中的 Pro275 招募 PKD2 到 TGN，然后通过其 C1a 结构域与二酰基甘油结合将 PKD2 锚定在 TGN 膜中。这两个过程对于 PKD2 介导的蛋白质运输都是至关重要的。
