Binds to the G-box motif (5'-CCACGTGG-3') of the rbcS-1A gene promoter. G-box and G-box-like motifs are cis-acting elements defined in promoters of certain plant genes which are regulated by such diverse stimuli as light-induction or hormone control. GBF2 is found to bind asymmetrically to the G-box. DNA-binding heterodimer. Interacts with GBF4 (PubMed:8146148). Interacts with BZIP16 and BZIP68 (PubMed:18315949). Found in both light and dark grown leaves. Belongs to the bZIP family.