Figure 6.

Reversibility of the light-induced activation of LHCII phosphorylation and fluorescence quenching. LHCII suspended in the phosphorylation buffer in darkness was transferred to the light (Dark > 220 μE) and incubated for 15 min, then transferred and incubated in darkness (>Dark) for 45 min to allow decay of the light-activated state and then re-exposed to the light (>220 μE) for 15 min. Samples were taken at each step, the kinase was added to each sample, and phosphorylation was allowed to proceed for 20 min in darkness. The fluorescence emission of the sample was measured at the end of each incubation period in the light or darkness, and the value of a sample kept in darkness as is taken as 100%; open and dashed bars, levels of LHCII fluorescence and phosphorylation, respectively; μE, μmol photons m⁻²⋅s⁻¹.