PsaD can form complexes with ferredoxin and ferredoxin-oxidoreductase in photosystem I (PS I) reaction center. PSAD may encode the ferredoxin-docking protein. Interacts with PGRL1A and PGRL1B. By light. Phosphorylated by a threonine specific thylakoid kinase in a light activated and redox-dependent manner. After Mass spectrometry, it is not clear if Ala-45 or Glu-46 is the N-terminus of the mature protein. Belongs to the PsaD family.