Fig. 4.

The effects of proteasome inhibitor (MG132) on phyA degradation. (A) Degradation kinetics of AtPhyA::GFP and K_R phyA mutant proteins. Three-day-old dark-grown seedling were incubated with DMSO or 50 µM MG132 for 3 h and then exposed to red light (12 µmole m⁻² s⁻¹). Twenty microgram aliquots of crude extract were separated on 8% SDS-PAGE gel, and the western blot was probed with anti-GFP antibody (top). The same blots were subjected to Coomassie blue staining (bottom) as a control. (B–E) Quantification of phyA levels in western blot bands. PhyA protein level was compared with the dark levels of each genotype as a control. Data are means ± SDs of three replicates. Statistical significance of the difference in expression according to DMSO or MG132 was determined using the t-test as implemented in IBM SPSS Statistics 21 with P < 0.05 considered statistically significant.