| Type: | Domain | Name: | Cystine knot, C-terminal |
| Description: | Four recent crystal structures of growth factors--nerve growth factor, transforming growth factor-beta, platelet-derived growth factor, and human chorionic gonadotropin--from four separate superfamilies revealed that these proteins are structurally related and share a common overall topology []. These proteins have very little sequence homology, but they all have an unusual arrangement of six cysteines linked to form a "cystine-knot" conformation. The active forms of these proteins are dimers, either homo- or heterodimers []. Because of their shape, there appears to be an intrinsic requirement for the cystine-knot growth factors to form dimers. This extra level of organisation increases the variety of structures built around this simple structural motif []. | Short Name: | Cys_knot_C |
