Sequence alignment between 7d3s(P) and UniProt seq P09683 (SECR_HUMAN):

P09683 (SECR_HUMAN): Secretin from Homo sapiens
                 10        20        30        40        50        60        70        80        90       100       110       120 
         ---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+-
UniProt: MAPRPLLLLLLLLGGSAARPAPPRARRHSDGTFTSELSRLREGARLQRLLQGLVGKRSEQDAENSMAWTRLSAGLLCPSGSNMPILQAWMPLDGTWSPWLPPGPMVSEPAGAAAEGTLRPR
PDB seq: ---------------------------HSDGTFTSELSRLREGARLQRLLQGLV-------------------------------------------------------------------
                                    ---------+---------+-------                                                                   
                                            10        20