Figure 3. Thylakoid protein phosphorylation during the photoperiod.

A, relative changes in the PSII and LHCII protein phosphorylation determined by immunoblotting analyses of SDS-PAGE separated thylakoid proteins with anti-phosphothreonine antibody. Thylakoids were prepared from leaves of the wild type plants harvested at the indicated time points during night or day (4, 7, 19 are the hours of the dark phase and 10, 13, 16 are the hours of the light phase of the photoperiod). Error bars represent S.D. of at least three independent experiments. B, immunoblot of thylakoid proteins from the stn mutants and wild type, as indicated, with anti-phosphothreonine antibody from Zymed Laboratories. Positions of the phosphorylated thylakoid proteins and of the molecular mass markers are indicated. Time points correspond to the highest and lowest phosphorylation of CP43 in the wild type plant leaves: after 12 hours of darkness (time point 4) and after 5 hours of light (time point 13).