Abscisic acid receptor PYR1 (PYR1)

Abscisic acid receptor PYR1 (also known as Pyrabactin resistance 1) is a critical intracellular sensor for the phytohormone abscisic acid (ABA), predominantly characterized in Arabidopsis thaliana and other plant species [1, 6]. It belongs to the PYR/PYL/RCAR family of receptors, which are members of the START domain-containing protein superfamily characterized by a hydrophobic ligand-binding pocket [2, 10]. PYR1 acts as a molecular switch in the plant's response to abiotic stressors like drought, salinity, and cold; in the absence of ABA, it exists as an inactive homodimer [3, 5]. Upon binding ABA or synthetic agonists such as pyrabactin or opabactin, PYR1 undergoes a conformational change involving gate and latch loops that allow it to bind and inhibit group A Type 2C protein phosphatases (PP2Cs) [1, 7]. This inhibition releases the repression of SnRK2 kinases, which subsequently activate downstream transcription factors to initiate stress-responsive gene expression, such as that leading to stomatal closure to conserve water [4, 11]. As a significant target in agrochemistry, PYR1 is utilized for developing synthetic ABA mimics that can be applied to crops to improve drought tolerance and yield stability [8, 14, 15].

Other names

Pyrabactin resistance 1Regulatory component of ABA receptor 11RCAR11ABI1-binding protein 6

Ligand-induced inhibition of Type 2C protein phosphatases (PP2Cs) through a gate-latch-lock conformational mechanism [1, 3, 10].