Takatsu H, Katoh Y, Shiba Y, Nakayama K
Institute of Biological Sciences and Gene Experiment Center, University of Tsukuba, Tsukuba Science City, Ibaraki 305-8572, Japan.
J Biol Chem. 2001 Jul 27;276(30):28541-5. doi: 10.1074/jbc.C100218200. Epub 2001 Jun 4.
GGA (Golgi-localizing, gamma-adaptin ear homology domain, ARF-binding) proteins are potential effectors of ADP-ribosylation factors, are associated with the trans-Golgi network (TGN), and are involved in protein transport from this compartment. By yeast two-hybrid screening and subsequent two-hybrid and pull-down analyses, we have shown that GGA proteins, through their VHS (Vps27p/Hrs/STAM) domains, interact with acidic dileucine sequences found in the cytoplasmic domains of TGN-localized sorting receptors such as sortilin and mannose 6-phosphate receptor. A mutational analysis has revealed that a leucine pair and a cluster of acidic residues adjacent to the pair are mainly responsible for the interaction. A chimeric receptor with the sortilin cytoplasmic domain localizes to the TGN, whereas the chimeric receptor with a mutation at the leucine pair or the acidic cluster is mislocalized to punctate structures reminiscent of early endosomes. These results indicate that GGA proteins regulate the localization to or exit from the TGN of the sorting receptors.
GGA（高尔基体定位、γ-衔接蛋白耳同源结构域、ARF结合）蛋白是ADP核糖基化因子的潜在效应蛋白，与反式高尔基体网络（TGN）相关，并参与从该区室的蛋白质运输。通过酵母双杂交筛选以及随后的双杂交和下拉分析，我们已经表明，GGA蛋白通过其VHS（Vps27p/Hrs/STAM）结构域，与TGN定位的分选受体（如sortilin和甘露糖6-磷酸受体）细胞质结构域中发现的酸性双亮氨酸序列相互作用。突变分析表明，一对亮氨酸以及该对亮氨酸相邻的一簇酸性残基主要负责这种相互作用。具有sortilin细胞质结构域的嵌合受体定位于TGN，而在亮氨酸对或酸性簇处发生突变的嵌合受体则错误定位于点状结构，类似于早期内体。这些结果表明，GGA蛋白调节分选受体在TGN的定位或从TGN的输出。
