Root: scop

Classes:

1. All alpha proteins (151)
2. All beta proteins (110)
3. Alpha and beta proteins (a/b) (113)
   Mainly parallel beta sheets (beta-alpha-beta units)
4. Alpha and beta proteins (a+b) (208)
   Mainly antiparallel beta sheets (segregated alpha and beta regions)
5. Multi-domain proteins (alpha and beta) (34)
   Folds consisting of two or more domains belonging to different classes
6. Membrane and cell surface proteins and peptides (12)
   Does not include proteins in the immune system
7. Small proteins (58)
   Usually dominated by metal ligand, heme, and/or disulfide bridges
8. Coiled coil proteins (5)
   Not a true class
9. Low resolution protein structures (16)
   Not a true class
10. Peptides (92)
    Peptides and fragments. Not a true class
11. Designed proteins (31)
    Experimental structures of proteins with essentially non-natural sequences. Not a true class