Figure 1

Correlations of human protein-coding gene properties with expression breadth and phyletic age. The numbers in the x-axis of panels a, c, e indicate the numbers of tissues in which genes are expressed. Phyletic groups in panels b, d, f are arranged according to their age, with 'cellular organisms' being the oldest and 'primates' the youngest. (a) Broadly expressed human proteins tend to be older, i.e., have homologs in more distantly related species. (b) Genes of different ages have distinct promoter architectures. (c-f) Gene function (according to GO and KEGG annotation) is correlated with both expression breadth (c, e) and phyletic age (d, f).