Department of Physiology and Biophysics, UAMS, Little Rock, AR, USA.
Sci Rep. 2016 Jul 7;6:29139. doi: 10.1038/srep29139.
The conserved oligomeric Golgi (COG) complex is a peripheral membrane protein complex which orchestrates tethering of intra-Golgi vesicles. We found that COG1-4 (lobe A) and 5-8 (lobe B) protein assemblies are present as independent sub-complexes on cell membranes. Super-resolution microscopy demonstrates that COG sub-complexes are spatially separated on the Golgi with lobe A preferential localization on Golgi stacks and the presence of lobe B on vesicle-like structures, where it physically interacts with v-SNARE GS15. The localization and specific interaction of the COG sub-complexes with the components of vesicle tethering/fusion machinery suggests their different roles in the vesicle tethering cycle. We propose and test a novel model that employs association/disassociation of COG sub-complexes as a mechanism that directs vesicle tethering at Golgi membranes. We demonstrate that defective COG assembly or restriction of tethering complex disassembly by a covalent COG1-COG8 linkage is inhibitory to COG complex activity, supporting the model.
保守的寡聚高尔基体（COG）复合物是一种位于质膜上的周边膜蛋白复合物，它协调着内高尔基体内囊泡的锚定。我们发现 COG1-4（A 叶）和 5-8（B 叶）蛋白组装体作为独立的亚复合物存在于细胞膜上。超分辨率显微镜显示，COG 亚复合物在高尔基体上空间分离，A 叶优先定位于高尔基体堆叠上，B 叶存在于囊泡样结构上，与 v-SNARE GS15 发生物理相互作用。COG 亚复合物与囊泡锚定/融合机制的成分的定位和特异性相互作用表明它们在囊泡锚定循环中具有不同的作用。我们提出并测试了一种新模型，该模型利用 COG 亚复合物的缔合/解离作为一种机制，指导高尔基体膜上囊泡的锚定。我们证明，COG 组装的缺陷或通过共价 COG1-COG8 连接限制 tethering 复合物的解离对 COG 复合物的活性具有抑制作用，这支持了该模型。
