State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Nat Commun. 2022 May 16;13(1):2703. doi: 10.1038/s41467-022-30179-w.
Protein sorting in the secretory pathway is essential for cellular compartmentalization and homeostasis in eukaryotic cells. The endoplasmic reticulum (ER) is the biosynthetic and folding factory of secretory cargo proteins. The cargo transport from the ER to the Golgi is highly selective, but the molecular mechanism for the sorting specificity is unclear. Here, we report that three ER membrane localized proteins, SUN3, SUN4 and SUN5, regulate ER sorting of leucine-rich repeat receptor kinases (LRR-RKs) to the plasma membrane. The triple mutant sun3/4/5 displays mis-sorting of these cargo proteins to acidic compartments and therefore impairs the growth of pollen tubes and the whole plant. Furthermore, the extracellular LRR domain of LRR-RKs is responsible for the correct sorting. Together, this study reports a mechanism that is important for the sorting of cell surface receptors.
蛋白质在分泌途径中的分拣对于真核细胞的细胞区室化和动态平衡至关重要。内质网（ER）是分泌货物蛋白的合成和折叠工厂。货物从 ER 向高尔基体的运输是高度选择性的，但分拣特异性的分子机制尚不清楚。在这里，我们报告说，三种 ER 膜定位蛋白 SUN3、SUN4 和 SUN5 调节富含亮氨酸重复受体激酶（LRR-RKs）向质膜的 ER 分拣。三重突变体 sun3/4/5 将这些货物蛋白错误分拣到酸性隔室，从而损害花粉管和整个植物的生长。此外，LRR-RKs 的细胞外 LRR 结构域负责正确的分拣。总之，这项研究报告了一种对于细胞表面受体分拣很重要的机制。
