Sequence alignment of APSRs. Sequence alignment of α-subunits of APSRs (A) and that of β-subunits of APSRs (B). The abbreviations DESGI, DESVH, THBPB, and ARCFU represent the different species D. gigas, D. vulgaris strain Hildenborough, T. plumbophilus, and A. fulgidus, respectively. The secondary structures are defined according to the APSR structure from D. gigas.