Class, derived from secondary structure content, is assigned
for more than 90% of protein structures automatically.
Architecture, which describes the gross orientation of
secondary structures, independent of connectivities, is currently assigned manually.
The topology level clusters structures according to their topological connections and numbers of
secondary structures. The homologous superfamilies cluster proteins with highly similar structures
and functions. The assignments of structures to fold groups and homologous superfamilies are
made by sequence and structure comparisons.
