We have previously identified the chloroplast translation initiation factor IF-2, or FUG1, as a GUN1 interactor based on co-immunoprecipitation and co-expression analysis (Tadini et al., 2016). To further investigate the functional relationship between these two proteins, the double mutant gun1-103 fug1-3 was generated by crossing the single gun1-103 knock-out mutant and the fug1-3 knock-down mutant. We performed comparative proteomics on gun1-103 and fug1-3, as well as on the double mutant gun1-103 fug1-3.