Emerging mechanisms to fine-tune receptor kinase signaling specificity

Organisms need to constantly inform their cellular machinery about the biochemical and physical status of their surroundings to adapt and thrive. While some external signals are also sensed intracellularly, a considerable share of external information is registered already at the plasma membrane (PM). Receptor kinases (RKs) are crucial for plant cells to integrate such cues from the environment, from microbes, or from other cells to coordinate their physiological response and their development. Early studies on RK signaling depicted the path from external signal to internal response in a linear fashion, but recent findings show that these cellular information highways are highly interconnected and pass signals through molecular intersections. In this review, we first discuss how individual RKs simultaneously contribute to the transduction and deconvolution of a multitude of signals by controlled assembly into diverse RK complexes, exemplified by FERONIA signaling versatility. We then elaborate on how cells can exert highly localized control over the assembly, interaction and composition of such complexes in order to attain essential cellular output specificity.