Fig 2. Kinases genes and proteins are more responsive than phosphatases.
A. Yeast phosphatases are differentially expressed in fewer perturbations relative to all genes in yeast (p = 0.032, Mann-Whitney test). The data refer to the 45 kinases, 15 phosphatases, and 2979 protein-coding genes that were differentially expressed in at least one perturbation. B. Kinases are significantly more involved in protein-protein interactions (PPIs) relative to phosphatases (*) or to all proteins (+). The numbers of kinases, phosphatases, and protein-coding genes for which PPI data were available, and the respective Mann-Whitney p-value per organism, were as follows: Yeast 135, 49, 4,925, p<10−10; plant 377, 89, 6,430, p = 0.008; fly 213, 85, 9,539, p = 0.032; mouse 311, 52, 5,527, p = 2*10−9; human 633, 177, 16,387, p = 9*10−7. C. The capacity of yeast kinases to undergo phosphorylation is significantly higher than the capacity of phosphatases. This is observed in data of manually-curated phosphorylation / de-phosphorylation interactions (denoted known events), p = 5.7*10−6; in phospho-peptide abundance measurements, p = 9.7*10−5; and in a dataset of conserved phosphorylation sites within protein sequences, p = 1.4*10−7 (Fisher exact test). Box plots show the values at the first, second and third quartiles. ***/+++ indicate p<10−6; ** indicate p<10−3; */+ indicates p<0.05.