Shaping Brassinosteroid Signaling through Scaffold Proteins

Abstract Cellular responses to internal and external stimuli are orchestrated by intricate intracellular signaling pathways. To ensure an efficient and specific information flow, cells employ scaffold proteins as critical signaling organizers. With the ability to bind multiple signaling molecules, scaffold proteins can sequester signaling components within specific subcellular domains or modulate the efficiency of signal transduction. Scaffolds can also tune the output of signaling pathways by serving as regulatory targets. This review focuses on scaffold proteins associated with the plant GLYCOGEN SYNTHASE KINASE3–like kinase, BRASSINOSTEROID-INSENSITIVE2 (BIN2), that serves as a key negative regulator of brassinosteroid (BR) signaling. Here, we summarize current understanding of how scaffold proteins actively shape BR signaling outputs and cross-talk in plant cells via interactions with BIN2.