Structural Classification of Proteins 2 - http://scop2.mrc-lmb.cam.ac.uk/
The Structural Classification of Proteins (SCOP) database provides a detailed and comprehensive description of the relationships of known protein structures. The classification is on hierarchical levels: the first two levels, family and superfamily, describe near and distant evolutionary relationships; the third, fold, describes geometrical relationships. The distinction between evolutionary relationships and those that arise from the physics and chemistry of proteins is a feature that is unique to this database so far. The sequences of proteins in SCOP provide the basis of the ASTRAL sequence libraries that can be used as a source of data to calibrate sequence search algorithms and for the generation of statistics on, or selections of, protein structures. - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC102479/
Удобно то, что с этой базы идут гиперссылки на Protein Data Bank и можно посмотреть визуальную картинку белков в 3D