RT Journal Article SR Electronic T1 Abscisic Acid Inhibits Type 2C Protein Phosphatases via the PYR/PYL Family of START Proteins JF Science JO Science FD American Association for the Advancement of Science SP 1068 OP 1071 DO 10.1126/science.1173041 VO 324 IS 5930 A1 Park, Sang-Youl A1 Fung, Pauline A1 Nishimura, Noriyuki A1 Jensen, Davin R. A1 Fujii, Hiroaki A1 Zhao, Yang A1 Lumba, Shelley A1 Santiago, Julia A1 Rodrigues, Americo A1 Chow, Tsz-fung F. A1 Alfred, Simon E. A1 Bonetta, Dario A1 Finkelstein, Ruth A1 Provart, Nicholas J. A1 Desveaux, Darrell A1 Rodriguez, Pedro L. A1 McCourt, Peter A1 Zhu, Jian-Kang A1 Schroeder, Julian I. A1 Volkman, Brian F. A1 Cutler, Sean R. YR 2009 UL http://science.sciencemag.org/content/324/5930/1068.abstract AB Type 2C protein phosphatases (PP2Cs) are vitally involved in abscisic acid (ABA) signaling. Here, we show that a synthetic growth inhibitor called pyrabactin functions as a selective ABA agonist. Pyrabactin acts through PYRABACTIN RESISTANCE 1 (PYR1), the founding member of a family of START proteins called PYR/PYLs, which are necessary for both pyrabactin and ABA signaling in vivo. We show that ABA binds to PYR1, which in turn binds to and inhibits PP2Cs. We conclude that PYR/PYLs are ABA receptors functioning at the apex of a negative regulatory pathway that controls ABA signaling by inhibiting PP2Cs. Our results illustrate the power of the chemical genetic approach for sidestepping genetic redundancy.