Fig. 4. HEN3 is closely related to CDK8. (A) A diagram of HEN3 protein with the serine-threonine kinase domain represented by the oval. (B) A Clustal W alignment of the kinase domains in HEN3 and human CDK8. Identical and similar amino acids are shaded. The amino acid positions and nature of the three hen3 alleles are indicated above the sequences. The cyclin-binding motifs of HEN3 and CDK8 are underlined. (C) A bootstrap consensus phylogenetic tree involving nine different human CDKs, CDK8 from Drosophila (DmCDK8), mouse (MmCDK8), Dictyostelium (DdCDK8) and yeast (Srb10p), three E type CDKs from plants, and the Arabidopsis CDKA (AtCDKA). Cdc2MsE and OsAAG46164 are CDKEs from alfalfa and rice, respectively. The tree was constructed using the neighbor joining method and the bootstrap consensus was generated from 1000 replications. The numbers represent the percentage occurrence of the nodes in the replications. Only the protein kinase domains from these proteins were used in the analysis. The CDK8 clade is indicated by the rectangle.