Dukhovny Anna, Yaffe Yakey, Shepshelovitch Jeanne, Hirschberg Koret
Department of Pathology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel.
J Cell Sci. 2009 Jun 1;122(Pt 11):1759-67. doi: 10.1242/jcs.039339. Epub 2009 May 12.
The cellular destination of secretory proteins is determined by interactions of their targeting motifs with coat-protein complexes. The transmembrane domain (TMD) of secretory proteins also plays a central role in their transport and targeting. However, a comprehensive model that considers both TMD- and targeting-sequence-mediated transport has never been advanced. We focused on the secretory transport of two fluorescently tagged membrane proteins: vesicular stomatitis virus G tsO45 (VSVG), which is a cargo protein that is a thermoreversible mutant, and the Golgi-resident protein GalT-CFP. A quantitative approach was applied to analyze, in living cells, secretory transport dynamics, as well as cargo concentration of YFP-tagged VSVG mutants with one, three, five, seven, eight or nine amino acids deleted from their TMD, as well as two or four amino acids added to their TMD. Changes in TMD length affected secretory transport dynamics and the extent of cargo concentration in the ER exit sites, demonstrating that the capacity of the transport machinery to concentrate cargo depends on the length of the TMD of the cargo protein.
分泌蛋白的细胞定位是由其靶向基序与衣被蛋白复合物的相互作用决定的。分泌蛋白的跨膜结构域（TMD）在其运输和定位中也起着核心作用。然而，一个同时考虑TMD和靶向序列介导运输的综合模型从未被提出过。我们聚焦于两种荧光标记膜蛋白的分泌运输：水泡性口炎病毒G tsO45（VSVG），它是一种货物蛋白，是一种热可逆突变体，以及高尔基体驻留蛋白GalT-CFP。我们采用定量方法来分析活细胞中的分泌运输动力学，以及从其TMD中缺失一、三、五、七、八或九个氨基酸，或在其TMD中添加两个或四个氨基酸的YFP标记的VSVG突变体的货物浓度。TMD长度的变化影响了分泌运输动力学以及内质网出口位点处货物浓缩的程度，这表明运输机制浓缩货物的能力取决于货物蛋白TMD的长度。
