Phosphorylation of SAMS, AMARA, and SP46 peptides by partially purified SnRK. 32P incorporation copurifying SuSy without further additions (lane 1), SAMS (lane 2), AMARA (lane 3), and SP46 (lane 4) peptides, revealed by autoradiography of Tricine-SDS-PAGE electrophoresis carried out on precast 4% to 20% polyacrylamide gradient gels. Molecular mass markers (in kilodaltons) are indicated on the left.