Sequence alignment between 4x6d(D) and UniProt seq P61769 (B2MG_HUMAN):

P61769 (B2MG_HUMAN): Beta-2-microglobulin from Homo sapiens
                 10        20        30        40        50        60        70        80        90       100       110         
         ---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------
UniProt: MSRSVALAVLALLSLSGLEAIQRTPKIQVYSRHPAENGKSNFLNCYVSGFHPSDIEVDLLKNGERIEKVEHSDLSFSKDWSFYLLYYTEFTPTEKDEYACRVNHVTLSQPKIVKWDRDM
         ...............................XXXXXXXXXX................................................XXXXXXXX......................
PDB seq: --------------------IQRTPKIQVYS----------FLNCYVSGFHPSDIEVDLLKNGERIEKVEHSDLSFSKDWSFYLLYYTE--------YACRVNHVTLSQPKIVKWD---
                             ---------+-          --------+---------+---------+---------+---------        --+---------+------   
                                     10                  30        40        50        60                  80        90