Sequence alignment between 3a6q(A) and UniProt seq Q46604 (FMNB_DESVM):

Q46604 (FMNB_DESVM): FMN-binding protein from Desulfovibrio vulgaris (strain DSM 19637 / Miyazaki F) 
                 10        20        30        40        50        60        70        80        90       100       110       120  
         ---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+--
UniProt: MLPGTFFEVLKNEGVVAIATQGEDGPHLVNTWNSYLKVLDGNRIVVPVGGMHKTEANVARDERVLMTLGSRKVAGRNGPGTGFLIRGSAAFRTDGPEFEAIARFKWARAALVITVVSAEQTL
         ............X.............................................................................................................
PDB seq: MLPGTFFEVLKNTGVVAIATQGEDGPHLVNTWNSYLKVLDGNRIVVPVGGMHKTEANVARDERVLMTLGSRKVAGRNGPGTGFLIRGSAAFRTDGPEFEAIARFKWARAALVITVVSAEQTL
         ---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+---------+--
                 10        20        30        40        50        60        70        80        90       100       110       120