Human KRAB-zinc finger proteins (KZFPs) and their evolution in the primate lineage. (A) Dots indicate relative chromosomal position of KZFP genes (defined by juxtaposed KRAB- and zinc finger-coding domains), with the color code indicative of age (gray for unassigned) and numbered clusters pointed to in black. Hollow circles indicate non-protein-coding genes. A higher magnification of Chromosome 19 is presented on top. Centromeres are indicated in light gray. (B) Phylogenetic tree of primate species used to calculate natural selection of human genes, with branch length indicating approximate time of divergence in million years (MYA). Silhouettes courtesy of PhyloPic (http://phylopic.org/). (C) Distribution of PAML dN/dS values of natural selection for KZFPs (red), nonKRAB ZFPs (blue), and all remaining genes in the genome (gray). (D) dN/dS distribution of primate-specific KZFPs (blue) and older (red) KZFP genes. (E) Spearman's correlation of the dN/dS values and estimated age of KZFP genes. The linear regression and 95% confidence interval are shown in red.
