COMMD1 Forms Oligomeric Complexes Targeted to the Endocytic Membranes via Specific Interactions with Phosphatidylinositol 4,5-Bisphosphate
COMMD1 Forms Oligomeric Complexes Targeted to the Endocytic Membranes via Specific Interactions with Phosphatidylinositol 4,5-Bisphosphate
复制标题
DOI：
10.1074/jbc.m804766200
复制
发表时间：
2009-01-02
影响因子：
4.8
通讯作者：
Lutsenko, Svetlana
中科院分区：
文献类型：
--
作者：
Burkhead, Jason L.;Morgan, Clinton T.;Lutsenko, Svetlana
铜代谢Murr 1结构域1（COMMD 1）是一种21 kDa的蛋白质，参与铜从肝脏的输出、NF-κ B信号传导、HIV感染和钠转运。COMMD的确切功能和COMMD 1执行其多重角色的机制尚不清楚。重组COMMD 1是一种可溶性蛋白，但在细胞中，COMMD 1主要被视为靶向细胞膜。使用与细胞器标记和细胞分级的共定位，我们确定COMMD 1位于内吞途径的囊泡中，而很少COMMD 1被检测到在trans-Golgi网络或溶酶体中。使用脂质点样阵列和脂质体研究COMMD 1向细胞膜募集的机制。COMMD 1在没有其他蛋白质的情况下特异性结合磷脂酰肌醇4，5-二磷酸（PtdIns（4，5）P-2），并且不结合结构脂质; PtdIns在位置4的磷酸化对于COMMD 1结合是必需的。蛋白水解敏感性和分子模拟实验确定了COMMD 1结构中的两个不同结构域。C-末端结构域似乎足以与脂质结合，因为全长和C-末端结构域蛋白均与PtdIns（4，5）P-2结合。在天然条件下，内源性COMMD 1在胞质溶胶和膜上形成大的寡聚复合物;与PtdIns（4，5）P-2的相互作用增加了寡聚物的稳定性。总之，我们的研究结果表明，COMMD 1是一个支架蛋白在一个独特的亚隔室的内吞途径，并提供了第一个线索，其作为一个调节器的结构无关的膜转运蛋白的作用。
Copper metabolism Murr1 domain 1 (COMMD1) is a 21-kDa protein involved in copper export from the liver, NF-kappa B signaling, HIV infection, and sodium transport. The precise function of COMMD and the mechanism through which COMMD1 performs its multiple roles are not understood. Recombinant COMMD1 is a soluble protein, yet in cells COMMD1 is largely seen as targeted to cellular membranes. Using co-localization with organelle markers and cell fractionation, we determined that COMMD1 is located in the vesicles of the endocytic pathway, whereas little COMMD1 is detected in either the trans-Golgi network or lysosomes. The mechanism of COMMD1 recruitment to cell membranes was investigated using lipid-spotted arrays and liposomes. COMMD1 specifically binds phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P-2) in the absence of other proteins and does not bind structural lipids; the phosphorylation of PtdIns at position 4 is essential for COMMD1 binding. Proteolytic sensitivity and molecular modeling experiments identified two distinct domains in the structure of COMMD1. The C-terminal domain appears sufficient for lipid binding, because both the full-length and C-terminal domain proteins bind to PtdIns(4,5)P-2. In native conditions, endogenous COMMD1 forms large oligomeric complexes both in the cytosol and at the membrane; interaction with PtdIns(4,5)P-2 increases the stability of oligomers. Altogether, our results suggest that COMMD1 is a scaffold protein in a distinct sub-compartment of endocytic pathway and offer first clues to its role as a regulator of structurally unrelated membrane transporters.