Fig. 4.

Reversible PSII-LHCII phosphorylation is defective in psb33 plants in fluctuating light conditions. Dynamics of thylakoid membrane phosphoproteins in response to fluctuating light conditions in wt and psb33. Thylakoids were isolated from plants at the end of the five dark–light periods (dark (Da1), low light for 2 h (LL1), high light for 2 h (HL), low light for 2 h (LL2), and darkness overnight (Da2)). On the left, a dilution series of dark (Da1) acclimated wild-type thylakoids shows the linear range of the antibody. (A) Immunoblot analyses of the PSII core (P-CP43, P-D2 and P-D1) and LHCII (P-LHCII) phosphoproteins from whole thylakoids were performed after SDS-PAGE. (B) Immunoblot showing the amounts of PsaB (above) and D1 (below) in the same samples as (A). Quantitative D1 protein levels, which have been normalized to Da1 D1 levels, are represented as numeric values below the D1 immunoblot. A Coomassie-stained PVDF membrane is shown as a loading control. (C) Immunoblots with specific antibodies against Lhcb1, P-Lhcb1, Lhcb2, P-Lhcb2, and PSB33 of whole-leaf protein extracts from wild-type and psb33 plants, highlighting the change in phosphorylation but not protein amounts of Lhcb1 and Lhcb2. A Coomassie-stained PVDF membrane is shown to demonstrate equal loading.