Abstract: Bioinformatics analysis has revealed about 4 000 proteins in chloroplasts; however, only about 1 000 proteins have been validated. Thus, we established an experimental system to verify predicted chloroplast proteins. At5g48790 was predicted to be an Arabidopsis chloroplast protein.The 178 bp segment of the 5' sequence of this gene was cloned and fused with GFP to construct a binary vector pMON530-cTP-GFP for genetic transformation. On confocal laser-scanning microscopy, green fluorescent signals were localized in chloroplasts in transgenic Arabidopsis plants. The results suggest that At5g48790 encodes a chloroplast protein. This experiment can also be used to investigate other proteins predicted to be located in chloroplasts in Arabidopsis．