CATH: Protein Structure Classification C.A. Orengo, A.D. Michie, S. Jones, M.B. Swindells, D.T. Jones, J.M. Thornton, University College, London
SCOP: Structural Classification of Proteins A.G. Murzin, S.E. Brenner, T.J.P. Hubbard, and C. Chothia, MRC, Cambridge
The Dali server L. Holm, A. de Daruvar & C. Sander, EMBL, Heidelberg
Blocks WWW Server Blocks are multiply aligned ungapped segments corresponding to the most highly conserved regions of proteins.