Substrate specificity of recombinant Arabidopsis PFT. Quantitative filter assay data are shown for recombinant Arabidopsis PFT in the presence of [1-3H]FPP, [1-3H]GGPP, and 32 distinct GFP-BD-CaaX substrates. The CaaX substrates are grouped with the variable amino acid indicated in red. Asterisks indicate PFT-catalyzed protein geranylgeranylation detectable after 4 days by SDS-PAGE and fluorography. The red line indicates background. The standard error of the mean is shown.