Brassinosteroid Signaling: A Paradigm for Steroid Hormone Signaling from the Cell Surface

Plants use the coordinated action of several small-molecule hormones to grow and develop optimally in response to a changing environment. Among these hormones are the brassinosteroids (BRs), the polyhydroxylated steroid hormones of plants. BRs bind a small family of leucine-rich repeat receptor kinases at the cell surface, thereby initiating an intracellular signal transduction cascade that results in the altered expression of hundreds of genes.