Type 2C protein phosphatases directly regulate abscisic acid-activated protein kinases in Arabidopsis

Taishi Umezawa, Naoyuki Sugiyama, Masahide Mizoguchi, Shimpei Hayashi, Fumiyoshi Myouga, Kazuko Yamaguchi-Shinozaki, Yasushi Ishihama, Takashi Hirayama, Kazuo Shinozaki

Research output: Contribution to journalArticlepeer-review

810 Citations (Scopus)


Abscisic acid (ABA) signaling is important for stress responses and developmental processes in plants. A subgroup of protein phosphatase 2C (group A PP2C) or SNF1-related protein kinase 2 (subclass III SnRK2) have been known as major negative or positive regulators of ABA signaling, respectively. Here, we demonstrate the physical and functional linkage between these two major signaling factors. Group A PP2Cs interacted physically with SnRK2s in various combinations, and efficiently inactivated ABA-activated SnRK2s via dephosphorylation of multiple Ser/Thr residues in the activation loop. This step was suppressed by the RCAR/PYR ABA receptors in response to ABA. However the abi1-1 mutated PP2C did not respond to the receptors and constitutively inactivated SnRK2. Our results demonstrate that group A PP2Cs act as 'gatekeepers' of subclass III SnRK2s, unraveling an important regulatory mechanism of ABA signaling.

Original languageEnglish
Pages (from-to)17588-17593
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number41
Publication statusPublished - Oct 13 2009
Externally publishedYes


  • LC-MS
  • PYR1
  • Protein phosphorylation
  • SnRK2

ASJC Scopus subject areas

  • General


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