Evolution of protein kinase substrate recognition at the active site
Binomial p-values were calculated for each motif and each species considered. The heat map cells are coloured according to the extent of enrichment for that particular motif and species (see legend, bottom right). The numbers in the column labels correspond to the sample size of unique S/T phosphorylation sites (15-mer). Prokaryotic phosphosite samples are coloured in purple. (Top) Enrichment of 3 common phosphorylation signatures (S/T-P, R-x-x-S/T, and S/T-x-x-D/E). (Bottom) Enrichment of 29 motifs discovered using the motif-x tool. Motifs in which the effector kinase has already been described in the literature are coloured in red. S/T, serine/threonine.