OPM was developed using the following databases and servers:
We are grateful to Dr. Henry I. Mosberg for scientific and administrative support, Drs. Aleksey Murzin and Kim Henrick for discussion of protein evolution and quaternary structure, Drs. Eugene Krissinel and Gabor Tusnady for helpful explanations of SSM and PDB_TM, and Drs. Simon Hubbard, Vladimir Maiorov, and Simon Sherman for provided software.