Figure 9: A proposed model for ABI1 degradation.
From: Degradation of the ABA co-receptor ABI1 by PUB12/13 U-box E3 ligases
(1) ABI1 interacts with and inhibits OST1. ABI1 can also interact with PUB12/13. (2) After ABA-bound PYR1 interacts with ABI1, protein kinases such as OST1 are released and activated to phosphorylate downstream targets including transcriptional factors (TFs) and SLAC1 in guard cells. (3) PUB12/13 are able to ubiquitinate ABI1 likely because of the conformational change of ABI1 after it interacts with PYR1 (with ABA) or PYL9 (with and without ABA). (4) The ubiquitinated ABI1 is degraded by 26S proteasomes. (5) The transcripts of ABI1 and other related PP2Cs are induced by ABA signaling.
