TABLE 1

Notations used in this article

SymbolsMeaning for the yeast protein-protein interaction dataa
a1No. of protein interaction partners for duplicate gene 1
a2No. of protein interaction partners for duplicate gene 2
sNo. of shared partners between gene 1 and gene 2
t (= a1 + a2s)Total no. of nonredundant partners for gene 1 and gene 2
AAverage no. of partners per singleton gene
SAverage no. of shared partners per randomly picked singleton pair
TAverage total no. of nonredundant partners per randomly picked singleton pair
δ (= |a1a2|)Absolute difference between a1 and a2
min (a1, a2)The smaller of a1 and a2
max (a1, a2)The bigger of a1 and a2
dSNo. of synonymous substitutions per synonymous site between a pair of duplicates
ISF [= 1 − (s + δ)/t]Subfunctionalization index
SFSubfunctionalization
NFNeofunctionalization
SNFSubneofunctionalization
  • a The number of interaction partners is substituted by the number of expression sites when human gene spatial expression pattern is concerned.