Figure 4

Example of native entanglements in the crystal structures of CAT-III and DDLB. The closed loop and crossing section of the threading segment of their entangled regions are colored red and blue, respectively. The loops are closed by noncovalent contacts between two residues (colored yellow), and the rest part of the protein is colored gray. (a) Representative native entanglement in CAT-III: the loop (colored red) is closed by a native contact between residues 8 and 77, and the threading segment consists of residues 177–208. (b) Representative native entanglement in DDLB: the loop (colored red) consists of residues 98–146, and the threading segment consists of residues 160–184.