Sequence alignment between 6hqb(E) and UniProt seq P12975 (PSAE_SYNY3):

P12975 (PSAE_SYNY3): Photosystem I reaction center subunit IV from Synechocystis sp. (strain ATCC 27184 / PCC 6803 / Kazusa) 
                 10        20        30        40        50        60        70    
         ---------+---------+---------+---------+---------+---------+---------+----
UniProt: MALNRGDKVRIKRTESYWYGDVGTVASVEKSGILYPVIVRFDRVNYNGFSGSASGVNTNNFAENELELVQAAAK
PDB seq: -ALNRGDKVRIKRTESYWYGDVGTVASVEKSGILYPVIVRFDRVNYNGFSGSASGVNTNNFAENELELVQ----
          --------+---------+---------+---------+---------+---------+---------+    
                 10        20        30        40        50        60        70