ABI1 Antibody – Rabbit Polyclonal

Function: Key component and repressor of the abscisic acid (ABA) signaling pathway that regulates numerous ABA responses, such as stomatal closure, osmotic water permeability of the plasma membrane (Pos), drought-induced resistance and rhizogenesis, response to glucose, high light stress, seed germination and inhibition of vegetative growth. During the stomatal closure regulation, modulates the inward calcium-channel permeability as well as the actin reorganization in guard cells in response to ABA. Involved in the resistance to the bacterial pathogen Pseudomonas syringae pv. tomato. Controls negatively fibrillin expression that is involved in mediating ABA-induced photoprotection. May be involved in ABA content regulation. Plays a role in the Pro accumulation in response to reduced water availability (low water potential). Required for the ABA negative regulation of the ethylene-induced hyponastic growth. Involved in acquired thermotolerance of root growth and seedling survival. Activates/represses SRK2E/OST1 in response to ABA-dependent stimuli, especially in stomata closure regulation involving SLAC1. Ref.8 Ref.9 Ref.10 Ref.11 Ref.12 Ref.13 Ref.14 Ref.15 Ref.16 Ref.17 Ref.18 Ref.19 Ref.20 Ref.21 Ref.22 Ref.23 Ref.24 Ref.26 Ref.27 Ref.28 Ref.29 Ref.30 Ref.31 Ref.32 Ref.33 Ref.34 Ref.35 Ref.37 Ref.38 Ref.39 Ref.40 Ref.41 Ref.42 Ref.43 Ref.44 Ref.45 Ref.47 Ref.48 Ref.50 Ref.51 Ref.52 Ref.53 Ref.55 Ref.57 Ref.58 Ref.60 Ref.61 Ref.63 Ref.66

Catalytic activity: A phosphoprotein + H2O = a protein + phosphate. Ref.16 Ref.25 Ref.27

Cofactor: Binds 2 magnesium or manganese ions per subunit. Ref.16 Ref.25

Enzyme regulation: Phosphatase activity repressed by oxidized GPX3 and phosphatidic acid (PA). PA is produced by PLD alpha 1 in response to ABA. Repressed by PYR/PYL/RCAR ABA receptors in an ABA-dependent manner. Ref.48 Ref.58 Ref.68 Ref.70

Subunit structure: Interacts with ATHB-6, CIPK15/PKS3, GPX3, SRK2E/OST1, SRK2D, SRK2I, SCAR1, SCAR2, SCAR3 and SCARL. Binds to the PA released by the phospholipase D alpha 1 (PLDALPHA1) in response to ABA during the stomatal closure regulation. Interacts with ABA-bounded PYR1, PYL1, PYL2, PYL3, PYL4, PYL5, PYL6, PYL7, PYL8, PYL9, PYL10, and with free PYL2, PYL3 and PYL4. Binds to RPL12B, CPK21 and CPK23. Ref.38 Ref.39 Ref.48 Ref.52 Ref.54 Ref.58 Ref.59 Ref.65 Ref.66 Ref.67 Ref.68 Ref.69 Ref.70 Ref.71 Ref.72 Ref.73

Subcellular location: Nucleus. Cytoplasm. Cell membrane; Peripheral membrane protein. Note: Associated to the plasma membrane when in complex with PA, subsequently to ABA signaling. Ref.48 Ref.63

Tissue specificity: Expressed in seeds and seedlings. In roots, confined to lateral root caps and columella cells. Ref.56 Ref.63

Induction: Repressed by MYB44. Induced by low temperature, drought, high salt, ABA and ethylene. Ref.36 Ref.46 Ref.48 Ref.56 Ref.58 Ref.61 Ref.64 Ref.68 Ref.70

Domain: The 'lock' site stabilizes the complex made of PP2C, ABA and PYR/PYL/RCAR receptor by keeping receptor 'gate' and 'latch' loops in closed positions.

Miscellaneous: Enhanced ABA signaling repressor activity by the proteasomal inhibitor MG132 accompanied by a cytoplasmic localization.Plants insensitive to ABA (abi1-1) are more resitant to P.syringae.

Sequence similarities: Belongs to the PP2C family.Contains 1 PP2C-like domain.

Biophysicochemical propertiespH dependence:Optimum pH is 8. Ref.25