Sequence alignment between 1b5a(A) and UniProt seq P00173 (CYB5_RAT):

P00173 (CYB5_RAT): Cytochrome b5 from Rattus norvegicus
                 10        20        30        40        50        60        70        80        90       100       110       120       130    
         ---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+----
UniProt: MAEQSDKDVKYYTLEEIQKHKDSKSTWVILHHKVYDLTKFLEEHPGGEEVLREQAGGDATENFEDVGHSTDARELSKTYIIGELHPDDRSKIAKPSETLITTVESNSSWWTNWVIPAISALVVALMYRLYMAED
PDB seq: -----DKDVKYYTLEEIQKHKDSKSTWVILHHKVYDLTKFLEEHPGGEEVLREQAGGDATENFEDVGHSTDARELSKTYIIGELHPDDRSKIAKPSETL-----------------------------------
              ---------+---------+---------+---------+---------+---------+---------+---------+---------+----                                   
                      10        20        30        40        50        60        70        80        90