Fig. 7.

Intermediate EF values are compatible with genuine envelope localization. A, Representative SDS-PAGE analysis. Each lane contains 15 μg of proteins. CCE, crude cell extract; MW, molecular weight; E, envelope fraction, S, stroma; T, thylakoid. RbcL, Large Subunit of Rubisco. LHCP, Light harvesting complex proteins. B, Validation of the multiple subplastidial localizations of FtsY protein by Western blotting. Experiment performed on Arabidopsis plants, using FtsY antibody. The expected MW of the mature form (i.e. after cleavage of its plastid transit peptide) of FtsY is 35.1 kDa. Values between brackets are % abundance in the envelope, stroma, and thylakoids, according to Ferro et al. (12), and the EF value (this work). As expected from previous data (see AT_CHLORO database), FtsY is shared between the three chloroplast sub-compartments (34% in Envelope, 32% in Stroma and 33% in Thylakoid). Note that although unambiguously present in the envelope membrane, the EF value (2.7) of FtsY is far below the average EF value of envelope proteins (i.e. 13, see Fig. 3). LHCP, Light harvesting complex proteins. HMA1, Heavy Metal ATPase 1. KARI, Ketol-acid reducto-isomerase.