FIGURE 6.
SOG1 is directly phosphorylated by SnRK1 in low ATP. (A,B) The SOG1 peptide was used as the kinase substrate in a Kinase-GloTM Luminescent assay. The reduction in ATP levels in the reaction mixture indicates the degree of phosphorylation by the (A) KIN10 or (B) KIN11 kinase. Error bars indicate standard error of three biological replicates. (C,D) In vitro kinase assays with Flag-tag-KIN10 (C) or Flag-tag-KIN11 (D) and Flag-tag-SOG1 as a substrate. Immunoblotting with the anti-FLAG antibody shows equal FLAG-tagged SOG1 protein was loaded (bottom panel). (E) SOG1-Myc transgenic plants were treated with DMSO or 20 μM of antimycin A (20AA). Total protein was separated by a SDS-PAGE gel with Phos-tag and used for immunoblotting with the anti-Myc antibody. In addition to the main band (a), slow migrating bands (b, c, c’) can be observed. From left; protein blot from plants treated with DMSO and 20AA; DMSO with λ protein phosphatase (λPP) treatment and 20AA with λPP treatment. CBB, Coomassie Brilliant Blue, staining shows equal loading.