Plants grown under different illumination levels undergo a long-term acclimation response (LTR) resulting in differences in their leaf morphology and chloroplast protein composition to maximise their growth. At the proteomic level, LTR involves modulating the stoichiometry of photosynthetic complexes within the thylakoid membrane through de novo synthesis and degradation of specific proteins. The signalling pathways that mediate LTR in relation to light intensity remain largely unknown, however earlier studies demonstrated a key role for the light-harvesting complex II (LHCII) serine-threonine kinase STN7. We explored the effects of mutant strains of Arabidopsis targeting STN7 and its cognate phosphatase TAP38 in the LTR to low, moderate and high illumination, employing label-free quantitative proteomic analysis.