ROP signalling and their activating ROPGEFs - Specificity in cellular signal transduction of plants

Abstract

Every cell constantly receives signals from its neighbours or the environment. In plants, most signals are perceived by RECEPTOR-LIKE KINASES (RLKs) and then transmitted into the cell. The molecular switches RHO OF PLANTS (ROP) are critical proteins for polar signal transduction and regulate multiple cell polarity processes downstream of RLKs. Many ROPregulating proteins and scaffold proteins of the ROP complex are known. However, the spatiotemporal ROP signalling complex composition still needs to be understood. Moreover, how specificity is achieved in different ROP signalling pathways within one cell still needs to be determined. This review gives an overview of the recent advances in ROP signalling and how specificity by downstream scaffold proteins can be achieved. The composition of the ROP signalling complexes is discussed, focusing on the possibility of the simultaneous presence of ROP activators and inactivators within the same complex to balance ROP activity. Furthermore, this review highlights the function of plant-specific ROPGEFs polarising ROP signalling and defining the specificity of the initiated ROP signalling pathway.

Keywords: Auxin; RECEPTOR LIKE KINASES (RLKs); ROP; ROPGEF; cell division; cell polarity; membrane domain; phytohormones; signalling; tip-growth.