PSAN; calmodulin binding; Encodes the only subunit of photosystem I located entirely in the thylakoid lumen. May be involved in the interaction between plastocyanin and the photosystem I complex. ; 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 (181 aa)