FIGURE 1.
Purification of Arabidopsis heterotrimeric G protein complexes. Purified Gα protein (100 μg) or a control buffer was incubated with the indicated guanine nucleotide (20 μm) before adding purified Gβγ protein (100 μg) or a control buffer. Samples were analyzed with a Superdex 200 size-exclusion FPLC column. Protein content was monitored by absorbance at 280 nm, and fractions were analyzed by SDS-PAGE. Note that buffer contained GDP for all samples with only Gβγ. For all panels, red lines trace the absorbance of Gα protein alone; blue lines trace the Gβγ dimer alone; and gray lines trace the Gα and Gβγ proteins together. A, chromatogram and Coomassie-stained gels for GPA1 (AtGα) and AGB1/AGG1 (Gβγ1) with GTPγS. B, same as A but with GDP. C, chromatogram for Gαi1 and AGB1/AGG1 with GDP or GDP-AlF4−. D, chromatogram for GPA1 and human Gβ1γ2 with GDP or GDP-AlF4− (AF). Vol, volume.