Figure 2.

D1 protein degradation in Arabidopsis Columbia and Landsberg ecotypes, and in mutants fah1, tt4–2YY6, tt4-W85, and tt5. Leaves were pulse-labeled with [³⁵S] Met for 3 h under 50 μmol m⁻² s⁻¹ PAR, rinsed, and chased for various periods of time at the PAR fluence indicated, in the presence (0.62 μmol m⁻² s⁻¹) or absence of a background of UV-B radiation. Following the exposure to radiation, plants were homogenized and the membrane proteins were isolated and fractionated by SDS/PAGE. Radiolabeled bands were detected by autoradiography and their degradation kinetics were determined as described (Greenberg et al., 1987). Values represent averages of data from several independent experiments (n = 4–8). se of the mean are shown.