Receptor for abscisic acid (ABA) required for ABA-mediated responses such as stomatal closure and germination inhibition. Inhibits the activity of group-A protein phosphatases type 2C (PP2Cs) in an ABA-independent manner but more efficiently when activated by ABA. Confers enhanced sensitivity to ABA (PubMed:19407143, PubMed:19624469, PubMed:19769575, PubMed:19889877, PubMed:23844015, PubMed:21658606). Can be activated by both (-)-ABA and (+)-ABA (PubMed:23844015). Mediates crosstalk between ABA and auxin signaling to regulate lateral root growth. Required for lateral root growth suppression by ABA. In response to auxin, promotes lateral root growth by enhancing MYB77-dependent transcription of the auxin-responsive gene IAA19. Enhances the abilities of MYB44 and MYB73 to activate IAA19 gene (PubMed:24894996). Monomer (PubMed:21658606). Homodimer. Binds ABA on one subunit only (By similarity). interacts with ABI1 and HAB1, and possibly with other PP2Cs (PubMed:19624469, PubMed:19769575, PubMed:19874541). Binds to CARs protein in an ABA-independent manner, both at the plasma membrane and in the nucleus. Interacts directly with CAR1 and CAR4 (PubMed:25465408). Interacts with MYB44, MYB73 and MYB77 in an ABA-independent manner (PubMed:24894996). Interacts with DDA1 (PubMed:24563205). Interacts with CARK1 in the cytosol (PubMed:29928509). Binds to ABI1 when phosphorylated by CARK1 (PubMed:29928509, PubMed:19624469, PubMed:19769575, PubMed:19874541, PubMed:21658606, PubMed:24563205, PubMed:24894996, PubMed:25465408) (By similarity). Interacts with AIP1 in the nucleus (PubMed:22404835). Localizes at the plasma membrane in the presence of a CAR protein (e.g. CAR1 and CAR4). A number of isoforms are produced. According to EST sequences. Down-regulated by abscisic acid (ABA). Upon interaction with ABA, the 'latch' and 'gate' loops change in conformation leading to a tight dimerization and the creation a surface that enables the receptor to dock into and inhibit the PP2C active site. Phosphorylated by CARK1 especially in response to abscisic acid (ABA); this phosphorylation promotes its stability and inhibitory ability to ABI1. Ubiquitinated in DDA1- and CDD complex-dependent manner (PubMed:24563205). Ubiquitination leads to its subsequent proteasomal degradation (PubMed:24563205). No visible phenotype under normal growth conditions, but mutant seedlings exhibit enhanced sensitivity of lateral root inhibition by abscisic acid (ABA), and reduced suppression of primary root growth by ABA. Belongs to the PYR/PYL/RCAR abscisic acid intracellular receptor family.