Abstract
Now it is established that major ABA signal is transduced through PYR-type receptor - PP2Cs - SnRK2s to various functional components. Among six (or nine) PP2Cs involved in ABA signaling, AHG1 and AHG3 are unique in their nuclear localization and higher expressions in seeds besides their slightly different amino acid sequences, implying specific functions of these two PP2Cs. To address this idea, we conducted a TAP experiments using a recombinant AHG1 protein and crude extracts in order to identify interacting proteins specific to these PP2Cs. Interestingly, a protein that is a component of a co-repressor complex was identified in these experiments. Y2H analysis revealed that the interaction between this protein and PP2C is specific to AHG1 and AHG3. In addition, these two PP2Cs interact with another component of the complex in Y2H experiments. The co-respressor complex is supposed to regulated JA, auxin and ABA responses. These observation indicate that AHG1 and AHG3 have an unique function; regulation of ABA response through modifying co-repressor complex.
