FIGURE 4.

RGTA1·RGTB1 prenylates cysteine residues in a variety of C-terminal sequences in vitro. The presence or absence of individual components in each reaction is indicated by a plus or minus sign, respectively. Four proteins were chosen to represent the four different types of C-terminal sequences found in Arabidopsis Rab GTPases: RABA1A for -CCXX (A), RABA2A for -CCXXX (B); RABF2A for -XCCX (C); and RABG2 for -XCXC (D). For each representative protein, two single-cysteine substitution mutants and one double-cysteine substitution mutant were generated and tested in the in vitro prenylation assay. Exposure time for autoradiography was 24 h. The Coomassie Blue staining shows that equal amounts of target proteins were used in each reaction within each panel. Faint bands are marked with asterisk to help visualization.