Cancer Research Centre and 2 Institute of Integrative Biology, University of Liverpool, Liverpool L3 9TA, England, UK.
J Cell Biol. 2010 Oct 18;191(2):367-81. doi: 10.1083/jcb.201008051. Epub 2010 Oct 11.
A key requirement for Rab function in membrane trafficking is site-specific activation by GDP-GTP exchange factors (GEFs), but the majority of the 63 human Rabs have no known GEF. We have performed a systematic characterization of the 17 human DENN domain proteins and demonstrated that they are specific GEFs for 10 Rabs. DENND1A/1B localize to clathrin patches at the plasma membrane and activate Rab35 in an endocytic pathway trafficking Shiga toxin to the trans-Golgi network. DENND2 GEFs target to actin filaments and control Rab9-dependent trafficking of mannose-6-phosphate receptor to lysosomes. DENND4 GEFs target to a tubular membrane compartment adjacent to the Golgi, where they activate Rab10, which suggests a function in basolateral polarized sorting in epithelial cells that compliments the non-DENN GEF Sec2 acting on Rab8 in apical sorting. DENND1C, DENND3, DENND5A/5B, MTMR5/13, and MADD activate Rab13, Rab12, Rab39, Rab28, and Rab27A/27B, respectively. Together, these findings provide a basis for future studies on Rab regulation and function.
Rab 功能在膜运输中的一个关键要求是通过 GDP-GTP 交换因子(GEFs)进行特异性激活,但大多数 63 个人类 Rab 没有已知的 GEF。我们对 17 个人类 DENN 结构域蛋白进行了系统表征,并证明它们是 10 个 Rab 的特异性 GEF。DENND1A/1B 定位于质膜上的网格蛋白斑,在胞吞途径中将志贺毒素激活到反式高尔基体网络中的 Rab35。DENND2 GEF 靶向肌动蛋白丝,并控制甘露糖-6-磷酸受体向溶酶体的 Rab9 依赖性运输。DENND4 GEF 靶向与高尔基体相邻的管状膜隔室,在那里它们激活 Rab10,这表明其在上皮细胞的基底外侧极化分拣中具有功能,与在顶部分选中作用于 Rab8 的非 DENND GEF Sec2 互补。DENND1C、DENND3、DENND5A/5B、MTMR5/13 和 MADD 分别激活 Rab13、Rab12、Rab39、Rab28 和 Rab27A/27B。总之,这些发现为 Rab 调节和功能的未来研究提供了基础。