Sample exploration workflow in PSPACE. The screenshots presented here show a progressive sequence of steps in a typical workflow using interaction operators in PSPACE. The reference set used in this workflow is the same reference set shown in Figure 5. (A) The FATCAT aligned and SCOP class hierarchy annotated reference set has a tetrahedron shape with mostly small proteins clustered at the apex of the tetrahedron. Zooming in on the apex and annotating the view find clusters of small proteins and peptides. (B) Applying a filter operator to select the SCOP fold hierarchy annotation, and a zoom operator to move closer to structures at the apex, we see that the clusters of small proteins and peptides from the previous view are comprised of knottins, defensin -like and metallothionein chains. (C) Applying a selection operator to two adjacent structures (1JfwA and 1z99A), followed by a JMOL comparison operator generates a JMOL view of the pairwise FATCAT alignment of the two selected structures. (D) Applying the annotation filter operator and selecting CATH architecture shows that most of the structures in this vicinity have not yet been classified by CATH, though for classified structures most appear to be of irregular, ribbon, and roll CATH architectures.