SHOU4 proteins regulate trafficking of cellulose synthase complexes to the plasma membrane (Curr. Biol.)

Plant cell walls provide mechanical support and define the extent and direction of cell expansion. Regulation of cellulose synthase determines cell wall load bearing and involves the receptor like kinases FEI1/FEI2. To gain further understanding of cell wall integrity regulation Polko et al. performed a suppressor screen of fei1/fei2. The group identified SHOU4, encoding a novel transmembrane protein showing no homology to previously identified functional domains. SHOU4 localized at the plasma membrane, where it acted as a negative regulator of cellulose synthase exocytosis. Functional mutation of SHOU4 and its closest paralog, SHOU4-like, resulted in dwarfed growth, thinner cell walls and aborted root hair development. Those results illustrate importance of mechanisms involved in cellulose synthase delivery to plasma membrane in developmental processes. Summary by Magdalena Julkowska) Curr. Biol. 10.1016/j.cub.2018.07.076