Stabilizes the interaction between PsaC and the PSI core, assists the docking of the ferredoxin to PSI and interacts with ferredoxin-NADP oxidoreductase. The G.violaceus PSI reaction center is composed of one copy each of PsaA,B,C,D,E,F,L,M and Z, and forms trimeric complexes. Belongs to the PsaE family.