Fig. 4From: Molecular evolution of HIV-1 integrase during the 20 years prior to the first approval of integrase inhibitorsSignificant couplings within the HIV-1 integrase. The size of the dots indicate the values of the evolutionary coupling terms ecij and are plotted mirrored for position i against position j. The dashed horizontal and vertical lines seperate the three functional domains of the integraseBack to article page