Figure 2.

D1 protein degradation in photoinactivated thylakoids—dependence on nucleotide concentration. (A) Effect on the extent of D1 protein loss. The level of remaining D1 protein was determined by Western blotting in photoinactivated samples that were incubated in darkness for 90 min in the presence of the indicated concentrations of ATP (▴) or GTP (●). (B) Autoradiograms showing the level of D1 protein and its 23-kDa fragment in samples photoinactivated (PI) and subsequently dark-incubated with concentrations of up to 0.2 mM GTP. (C) Effect on the accumulation of the 23-kDa fragment of the D1 protein. The relative amounts of the proteolytic fragment were determined in samples treated as in A.