Park Misoon, Lee Daeseok, Lee Gil-Je, Hwang Inhwan
Division of Molecular and Life Sciences, Center for Plant Intracellular Trafficking, Pohang University of Science and Technology, Pohang 790-784, Korea.
J Cell Biol. 2005 Aug 29;170(5):757-67. doi: 10.1083/jcb.200504112. Epub 2005 Aug 22.
Organellar proteins are sorted by cargo receptors on the way to their final destination. However, receptors for proteins that are destined for the protein storage vacuole (PSV) are largely unknown. In this study, we investigated the biological role that Arabidopsis thaliana receptor homology region transmembrane domain ring H2 motif protein (AtRMR) 1 plays in protein trafficking to the PSV. AtRMR1 mainly colocalized to the prevacuolar compartment of the PSV, but a minor portion also localized to the Golgi complex. The coexpression of AtRMR1 mutants that were localized to the Golgi complex strongly inhibited the trafficking of phaseolin to the PSV and caused accumulation of phaseolin in the Golgi complex or its secretion. Co-immunoprecipitation and in vitro binding assays revealed that the lumenal domain of AtRMR1 interacts with the COOH-terminal sorting signal of phaseolin at acidic pH. Furthermore, phaseolin colocalized with AtRMR1 on its way to the PSV. Based on these results, we propose that AtRMR1 functions as the sorting receptor of phaseolin for its trafficking to the PSV.
细胞器蛋白在前往其最终目的地的途中由货物受体进行分选。然而，针对运往蛋白储存液泡（PSV）的蛋白质的受体在很大程度上尚不清楚。在本研究中，我们调查了拟南芥受体同源区域跨膜结构域环H2基序蛋白（AtRMR）1在蛋白质向PSV运输过程中所起的生物学作用。AtRMR1主要共定位于PSV的液泡前区室，但也有一小部分定位于高尔基体复合体。定位于高尔基体复合体的AtRMR1突变体的共表达强烈抑制了菜豆蛋白向PSV的运输，并导致菜豆蛋白在高尔基体复合体中积累或分泌。免疫共沉淀和体外结合试验表明，AtRMR1的腔结构域在酸性pH条件下与菜豆蛋白的COOH末端分选信号相互作用。此外，菜豆蛋白在前往PSV的途中与AtRMR1共定位。基于这些结果，我们提出AtRMR1作为菜豆蛋白运往PSV的分选受体发挥作用。
