Figure 2.

Kinetics of light activation of native and recombinant LHCII phosphorylation by the partially purified protein kinase. (A) Autoradiogram of isolated native LHCII phosphorylation in the light and darkness. (B) Quantification (average of three experiments ± 10%) of autoradiograms from similar experiments using LHCII or histone-S-III as substrates. (C) Phosphorylation of recombinant LHCII. The radioactivity incorporated in the light-incubated phosphorylation assay (nmol ³²P-mg protein⁻¹ at the end of the incubation) is taken as the maximal value for each substrate [4.6 and 7.5 for native LHCII and histone and 3.0 and 1.5 for the recombinant LHCII reconstituted with pigments (Rec. LHCII) and the apoprotein, (Apo. LHCII), respectively]; the values for the recombinant N-terminal truncated LHCII (Trun. LHCII) reconstituted with pigments are within the background noise level of the assay (about 0.1 nmol ³²P-mg protein⁻¹); open and dotted symbols, light- and dark-incubated samples, respectively.