Figure 3. Distinct sequence elements in the transit peptide of TPI correlate with either general or P-specific chloroplasts import.

(A) Sequences of WT_TPI and corresponding alanine substitution mutants. CS – cleavage site; TPI – triosephosphate isomerase. (B) Quantification of GFP signals in transfected protoplasts (WT_TPI; I – VIII mutant GFP-fusion constructs). Transfected protoplasts were counted and the expression pattern of GFP was categorized in general or P-specific import into the chloroplasts and shown as import efficiency relative to WT_TPI in percent. Quantification was performed as a blind study to reduce subjective bias as explained in Material and Methods. The means of four independent biological replicates are shown relative to WT_TPI. Error bars indicate standard error of the mean. Numbers indicate p-values from Student’s t-test. (C) Representative confocal images for all tested GFP-fusion constructs in young protoplasts (n > 5).