Control of ROP function by membrane lipids during plant exocytosis and endocytosis

Integral membrane proteins are important for the physiology of a plant. Examples for plasma membrane-integral proteins with major physiological roles include cellulose synthase complexes, for instance the subunits CesA3 or CesA6; cell surface receptors, such as FLAGELLIN-SENSITIVE 2 (FLS2); NADPH-oxidases, such as RESPIRATORY BURST OXIDASE HOMOLOG D (RbohD); or auxin exporters, such as PIN-FORMED (PIN) proteins; and many others. In contrast to soluble proteins, which may associate peripherally with membranes by various means, integral membrane proteins are firmly embedded in membranes and have to be delivered to their target membranes by vesicle trafficking. The dynamic balance between insertion of an integral membrane protein into and its recycling from a membrane defines its membrane lifetime and thus determines functional aspects of the membrane. Spatial control of insertion and recycling of membrane proteins can result in their accumulation in certain areas of the plasma membrane, giving rise to key aspects of cell polarization (in plants e.g., for PIN proteins). Despite their importance, in plants the factors directing and balancing exocytosis/protein insertion and endocytotic recycling at the plasma membrane are currently not understood at a molecular level. This project aims to better understand the regulatory interplay of membrane phospholipids with monomeric GTPases of the Rho of plants (ROP) family in this context in plants.