Figure 11.

Working model showing how TAP46 stabilizes ABI5 and protects ABI5 from the action of PP2A or PP2A-ls in plant cells. ABI5 is phosphorylated upon ABA treatment and becomes active in triggering gene expression. Binding of TAP46 to ABI5 stabilizes ABI5 and prevents PP2A or PP2A-ls (e.g. PP6 or PP4) from removing the phosphate on ABI5, binding of TAP46 to PP2A or PP2A-l may prevent PP2A or PP2A-l from binding to ABI5, or the binding of TAP46 to ABI5 may prevent PP2A or PP2A-l from binding to ABI5. Whatever the mechanisms, the TAP46’s involvement is a positive factor in stabilizing ABI5 and keeping ABI5 in phosphorylated form, thereby staying active.