Updated project metadata. The light reactions of photosynthesis couple electron and proton transfers across the thylakoid membrane, generating NADPH for carbon fixation and a proton motive force (dominated by ΔpH in chloroplasts) to drive ATP production by the ATP synthase complex. Regulation of NADPH and ATP levels to meet metabolic requirements alongside the dissipation of excess solar energy when it exceeds these requirements are critical to plant growth under fluctuating light environments. To investigate mechanisms involved in the regulation of the light reactions of photosynthesis, we describe proteomic comparisions between two mutant Arabidopsis strains and their respective wild-type background strains: (1) hope2 (ATP synthase γ1-subunit G143D mutant vs. wild-type background Col-0) and (2) pgr5 (impaired stability of the Proton Gradient Regulation 5 (PGR5) protein vs. wild-type background gl1).