Ben-Tekaya Houchaima, Miura Kota, Pepperkok Rainer, Hauri Hans-Peter
Department of Pharmacology and Neurobiology, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland.
J Cell Sci. 2005 Jan 15;118(Pt 2):357-67. doi: 10.1242/jcs.01615. Epub 2005 Jan 4.
The endoplasmic reticulum-Golgi intermediate compartment (ERGIC) defined by the cycling lectin ERGIC-53 consists of tubulovesicular clusters, but it is unknown if these membranes are transport vehicles or stationary entities. Here, we show by live imaging that GFP-ERGIC-53 mainly localizes to long-lived stationary and some short-lived highly mobile elements. Unlike the anterograde marker VSV-G-GFP, GFP-ERGIC-53 does not vectorially move to the Golgi upon exit from the ERGIC, as assessed by a novel quantitative vector field method. Dual-color imaging of GFP-ERGIC-53 and a secretory protein (signal-sequence-tagged dsRed) reveals that the stationary elements are sites of repeated sorting of retrograde and anterograde cargo, and are interconnected by highly mobile elements. These results suggest that the ERGIC is stationary and not simply a collection of mobile carriers that mediate protein traffic from endoplasmic reticulum to Golgi.
由循环凝集素ERGIC-53所定义的内质网-高尔基体中间区室(ERGIC)由管状囊泡簇组成,但这些膜是运输载体还是固定实体尚不清楚。在这里,我们通过实时成像显示,GFP-ERGIC-53主要定位于长寿命的固定元件和一些短寿命的高移动性元件。与顺行标记VSV-G-GFP不同,通过一种新型定量向量场方法评估,GFP-ERGIC-53从ERGIC退出后不会向高尔基体定向移动。GFP-ERGIC-53与分泌蛋白(信号序列标记的dsRed)的双色成像显示,固定元件是逆行和顺行货物重复分选的位点,并通过高移动性元件相互连接。这些结果表明,ERGIC是固定的,而不仅仅是介导蛋白质从内质网到高尔基体运输的移动载体的集合。