Figure 4: Model of interactions within the Mediator kinase module. All of the paralogs of the Mediator kinase module are shown (MED12/12L, MED13/13L, and CDK8/19). Positive interactions observed in Mediator-HaloTag complex isolations by mass spectrometry and Western blots (Figures 3a and b) are depicted with a solid black line, and those which are mutually exclusive are shown in red. Each of the paralogs are found to be mutually exclusive of one another, yet are not exclusive of any other kinase module member. This interaction map allows for a maximum of possible 8 complex configurations of the kinase module.