Sequence alignment between 5kaf(X) and UniProt seq Q9F1R6 (PSBX_THEEB):

Q9F1R6 (PSBX_THEEB): Photosystem II reaction center protein X from Thermosynechococcus vestitus (strain NIES-2133 / IAM M-273 / BP-1) 
                 10        20        30        40 
         ---------+---------+---------+---------+-
UniProt: MTITPSLKGFFIGLLSGAVVLGLTFAVLIAISQIDKVQRSL
PDB seq: -TITPSLKGFFIGLLSGAVVLGLTFAVLIAISQIDKVQR--
          --------+---------+---------+---------  
                 10        20        30