Skip to main content
. 2014 Apr 7;165(2):534–549. doi: 10.1104/pp.113.231993

Figure 1.

Figure 1.

Light intensity regulated the reversible phosphorylation of maize chloroplast PPDK at Thr-527. A, Identification of phosphorylated Thr-527 of PPDK in illuminated maize seedlings. The top gel shows a western blot of maize PPDK. The protein was extracted from 6-d-old green maize seedlings that had been illuminated for 12 h. The specific antibody raised against phosphorylated Thr-527 of PPDK detected six spots, which were visible in a pearls on a string pattern on the PVDF membrane. The corresponding 2DGE map (bottom gel) highlights the six PPDK isoforms (75–98 kD, pI 5.1–5.6). The graph at bottom displays the phospho-MS/MS spectra observed in all six spots (m/z 618.78, charge 2+). Ions corresponding to y and b fragments of the GGMTSHAAVVAR sequence are labeled and shown in the corresponding sequence insets. The assignment of the phosphorylated Thr-527 site was deduced from the mass of b and y ions. B to D, The gels at top show variations at Thr-527 and the abundance of PPDK in maize seedlings exposed to different light regimens (varied intensity of light); the graphs at bottom illustrate the correlations between PPDK phosphorylation levels, abundance, and activity. The triangles, squares, and circles represent PPDK activity, phosphorylation levels, and abundance, respectively. Chl, Chlorophyll.