Sequence alignment between 4zfn(A) and UniProt seq Q97W22 (Q97W22_SULSO):

Q97W22 (Q97W22_SULSO): Purine phosphoribosyltransferase (GpT-2) from Saccharolobus solfataricus (strain ATCC 35092 / DSM 1617 / JCM 11322 / P2)
                 10        20        30        40        50        60        70        80        90       100       110       120       130       140       150       160       170         
         ---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------
UniProt: MVEYHIPSWDEIEDAVFSIGEALVKSNYIPDVLIAVLTGGIIPAKLLSDLLDLKVIRYIDIKFYRSVGKTESKPVIRSVYTDSLEGKKVLVVDDVADTGETLEAVSNVITMFNPAKVMTAALYLKPWSKRIPDFYYKQIDKWIIFPWDKWDVVRENSNVPVDKKERFLNLYNQLLKIRK
         ..................................................................XXXX.............................................................................................................
PDB seq: --EYHIPSWDEIEDAVFSIGEALVKSNYIPDVLIAVLTGGIIPAKLLSDLLDLKVIRYIDIKFYRS----ESKPVIRSVYTDSLEGKKVLVVDDVADTGETLEAVSNVITMFNPAKVMTAALYLKPWSKRIPDFYYKQIDKWIIFPWDKWDVVRENSNVPVDKKERFLNLYNQLLKIRK
           -------+---------+---------+---------+---------+---------+------    ---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------
                 10        20        30        40        50        60                  80        90       100       110       120       130       140       150       160       170