Figure 8.

Processing of the N-terminal domain of CGS is specifically associated with folates starvation and occurs in several plant species. A, Soluble protein extracts were prepared from Arabidopsis cells grown for 72 h in culture medium supplemented with the following compounds, alone or in combination: 100 μm MTX, 100 μm sulfanilamide, 0.5 mm 5-formyl-THF, and 1 mm Met. Soluble proteins (30 μg) were extracted and analyzed by western blot with polyclonal antibodies against CGS. B, Leaf discs from pea and maize were floated for 8 d in petri dishes containing control medium or supplied with both MTX (100 μm) and sulfanilamide (100 μm). Soluble proteins (5 μg) prepared from control or MTXS-treated leaf discs were combined with an Arabidopsis protein extract (20 μg) containing MCGS and incubated for 1 h at 25°C before performing immunoblot analysis.