FIGURE 4.

Cullin modification and accumulation in csn mutants. A, total protein extracts from 7-day-old seedlings were analyzed by immunoblotting with anti-CUL1, anti-CUL3A, anti-CUL4 and anti-HSC70 antibodies. Immunodetection of cytosolic/nuclear HSC70 was used as the loading control. Open and filled arrowheads correspond to unmodified and RUB-modified cullins, respectively. One representative experiment is shown. wt, wild type. B and C, densitometric analysis was performed on anti-CUL1 and anti-CUL3A immunoblots to determine the relative proportion of RUB-modified cullin (B) and total cullin steady-state levels (C) (unmodified plus RUB-modified) for CUL1 or CUL3A protein. Error bars indicate S.D. between three independent biological replicates.