Figure 1. Overview of how the hpatch-fast score updates in response to a sequence substitution.

Consider a substitution from tyrosine to asparagine at position (node) 6. Each of the neighbors within 10 Å (solid circle) of node 6 - nodes 2, 5, 7, 9 and 10 (indicated by arrows) - updates its record of the total amount of hydrophobic accessible surface area (hASA) within 10 Å assuming the substitution is accepted. The sum of the change in the hpatch-fast score at node 6 and all of the neighboring nodes becomes the hpatch-fast score change for the substitution. The table shows how the hASA and hpatch-fast score change at all of the nodes. Dashed circle, neighbors within 10 Å of node 2.