Abstract

Musical Chairs The plant hormone abscisic acid (ABA) helps plants to respond to changes in the environment, such as drought. Physiological responses are initiated when ABA binds to its receptor. In the absence of ABA, downstream kinases are held inactive by phosphatases. Soon et al. (p. 85 , published online 24 November; see the Perspective by Leung ) now show that both the hormone-receptor complex and the downstream kinase bind to the same site on the phosphatase. Thus, in the presence of hormone, the phosphatase is occupied and unable to interfere with downstream kinase activity.