纤维素是由纤维素合酶（CESA）复合物（CSC）在植物细胞的质膜上产生的。 CSC被组装在内膜系统中，然后运至质膜。 因为CESA仅在质膜中起作用，所以控制CSC分泌可调节纤维素的合成。 我们确定了一个家族的七个跨膜域的蛋白质（7TMs）的成员，这些成员对细胞壁完整性应激期间的纤维素生产很重要。 7TMs通常与鸟嘌呤核苷酸结合（G）蛋白信号传导相关，我们发现影响Gβγ二聚体的突变体对7tm突变体进行了表型复制。 出乎意料的是，这些7TM位于Golgi / trans-Golgi网络中，在那里它们与G蛋白成分相互作用。 本研究，7TM和Gβγ调节CESA的运输，但不影响一般蛋白质的分泌。 我们的研究结果概述了G蛋白偶联模块如何调控CESA转运，并揭示了该过程中的缺陷导致对细胞壁完整性应激的反应加剧。
Cellulose is produced at the plasma membrane of plant cells by cellulose synthase (CESA) complexes (CSCs). CSCs are assembled in the endomembrane system and then trafficked to the plasma membrane. Because CESAs are only active in the plasma membrane, control of CSC secretion regulates cellulose synthesis. We identified members of a family of seven transmembrane domain-containing proteins (7TMs) that are important for cellulose production during cell wall integrity stress. 7TMs are often associated with guanine nucleotide-binding (G) protein signaling and we found that mutants affecting the Gβγ dimer phenocopied the 7tm mutants. Unexpectedly, the 7TMs localized to the Golgi/trans-Golgi network where they interacted with G protein components. Here, the 7TMs and Gβγ regulated CESA trafficking but did not affect general protein secretion. Our results outline how a G protein-coupled module regulates CESA trafficking and reveal that defects in this process lead to exacerbated responses to cell wall integrity stress.
