is a novel hierarchical classification of protein domain structures, which clusters proteins at four major levels,
Class(C), Architecture(A), Topology(T) and Homologous superfamily (H).
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 toplogical connections and numbers of
secondary structures. The homologous superfamilies cluster proteins with highly similar structures and functions.
The assignments of structures to toplogy families and homologous superfamilies are made by sequence and structure comparisons.
Here you can browse by CATH structural classifications (v4.0.0