Figure 3.

Characterization of PMSR4 expression in wild-type and transgenic Arabidopsis plants underexpressing PMSR4. RNA was isolated from 10-d-old wild-type (WT) and underexpressing (35S∷anti-PMSR4) plants and subjected to RT-PCR analysis. Actin was used as an internal control. The PMSR4 protein content of the plants was determined by western blot (labeled PMSR4 in the figure). A, Gene-specific primers as described in “Materials and Methods” were used to determine the level of the endogenous mRNA (labeled PMSR4). The western blot is in the lowest row. Isolated chloroplasts from 4-week-old plants were used for the protein expression analysis (PMSR4). For the westerns blots, 20 μg of protein were separated by SDS-PAGE, blotted onto a nitrocellulose membrane, and reacted with anti-PMSR antibodies. B and C, AAT activity gel and western-blot loading control, respectively, similar to those shown in Figure 1.