Figure 5

Acquisition of protein links and test of preferential attachment. Left panel. The relationship between the connectivity of a gene present at the root of the tree and its connectivity in the yeast (S. cerevisiae). Based upon 295 genes present at the root and in yeast. Line is 1:1 relationship. Right panel. The relationship between the number of connections acquired between the root of the tree and yeast (final-initial connectivity) and initial connectivity. Preferential attachment predicts a positive relationship. The regression line is positive but the weak relationship (r² = 0.03, slope = 0.018, p < 0.004), is not sufficient to produce a power-law scaled network (see text).