Protein backbone angles can be shown in a Ramachandran Plot along with probability contours (green lines) from a reference set of well-determined structures. Each amino acid residue is shown as a dot in a graph of φ vs. ψ, more commonly known as a Ramachandran plot or Ramachandran map. Residues are shown as blue dots, or when selected, as red dots. In the example, all helix residues have been selected. Conversely, clicking a dot in the plot will select the corresponding residue in the structure. When the plot has mouse focus, the cursor position (x = φ, y = ψ) is reported under the plot.

Mutations that inactivate the tumor suppressor p53 are found in over 50% of human cancers, and most of the cancer-associated mutations are within its DNA-binding domain. The image shows a tetramer of the p53 DNA-binding domain complexed with DNA (Protein Data Bank entry 2ac0). The tetramer subunits are shown as light blue, green, orange, and yellow ribbons, with red spheres marking several major "hot spots" of mutation. The DNA is shown in purple and blue. (More samples...)