Simplified example for building a FEATURE model. A. An example of a positive site (left) and negative site (right), and their respective microenvironments. Properties are calculated in concentric spherical shells centered on each site (star symbol). B. FEATURE vectors calculated from the images in A, with oxygen atom count being the first property, and carbon atom count the second. The vectors are divided by shell for clarity. C. An example of a visualized FEATURE model is shown, based on the FEATURE vectors in B, and images in A. In Shell 2, oxygen atoms are more abundant in the positive site (5 counts) than in the negative site (1 count) and so oxygen atom count is considered a significantly enriched property in Shell 2 of the model. In contrast, carbon atom count is less abundant in the positive site (0 counts) compared to the negative site (8 counts), so carbon atom count is considered a significantly depleted property in Shell 2 of the model. In Shell 3, both the positive and the negative sites have 1 oxygen atom, so the model contains no significant difference for oxygen atom count in Shell 3.
Halperin et al. BMC Genomics 2008 9(Suppl 2):S2 doi:10.1186/1471-2164-9-S2-S2