Proteins in the VEBD were mapped to their corresponding family levels based on their accession code. Non-defined levels were labelled as 'Other'. On levels L1 and L2, small-sized families were grouped into larger families as follows. L1 tags 'Auxiliary', 'Unclassified', 'Structural', and 'Surface' were grouped into 'Other'. L2 tags 'Primary active', 'Ligase', 'Isomerase', and 'Writer' were grouped into 'Other'. Additionally, all G protein-coupled receptor L2 tags were grouped into a single L2 family, 'GPCR'.