Figure 5.

(A) X-ray crystallographic structure of a p21 model peptide (residues 139–160) bound to PCNA [PDB ID 1AXC.⁴³ The helical region (p21 residues 146–151) is highlighted in purple, while the extended C-terminus (p21 residues 152–160) is depicted in cyan. Only residues of p21 included in our model peptide (145–160) are shown. (B) Structure of the p21 model peptide alone. (C) Comparison of corresponding local conformational preferences in models of the unbound form of p21(145–164). Regions for which models of the unbound form include local conformations which match the bound form crystal structure are indicated.