May function in mediating the binding of the antenna complexes to the PSI reaction center and core antenna. Plays an important role in docking plastocyanin to the PSI complex. Does not bind pigments. Interacts with GRF5, GRF7, GRF9 and GRF10. The transit peptide is the site of PSAN that associates with 14-3-3. The N-terminal Edman sequence is 2 amino acids down-stream of the N-acetylated terminal peptide identified by mass spectrometry. This suggests an additional processing. Belongs to the psaN family.