LC-MS/MS of chloroplasts from WT plants and fractionated the proteins into the membrane and stroma fractions

To confirm the localization of GCSC1 to chloroplast vesicle rather than in the stroma, we purified chloroplasts from WT plants and fractionated the proteins into the membrane and stroma fractions. Quantification of proteins by liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed that GCSC1 was present only in the membrane fractions, co-existing with several chloroplast membrane proteins.