QSbio needs to compare QSs from PDB with predictions from PISA, EPPIC, and QSalign/anti-QSalign. Comparing QSs between PDB and PISA is achieved with the full QS superimposition approach described above (Figure S2). However, to compare QSs between PDB and EPPIC, we must employ a different strategy because EPPIC provides pairwise interface information (as opposed to assembly information). We therefore mapped pairwise information from EPPIC onto QSs from PDB using the following approach. First, each QS from PDB was decomposed into pairs of chains, using all pairs burying >90 Å2. Each pair was subsequently matched to an interface group from EPPIC by structural superposition. Each interface group in EPPIC is classified as being either biological (green) or non-biological (magenta). In the case where all subunits of the QS could be linked by biological contacts, the QS was deemed to match EPPIC (example 1) and otherwise it was inferred as non-matching (example 2).