Distribution of positively selected amino acid residues mapped onto the surface of TLR1 family protein structures. The protein structures are from Jin et al. (2007) and Kang et al. (2009). The N, Central and C regions are defined in Table 1. The number represents the leucine-rich repeats. The regions in red, blue and cyan represent the TLR1/TLR6 and TLR2 interface, the ligand binding domain, and the region encompassing both interface and ligand binding, respectively. Pink ball and stick figures represent those amino acid sites under positive selection in mammals. Green and multi-coloured ball and stick figures represent amino acid sites under positive selection in avian TLR2-like proteins. Blue ball and stick figures represent sites within the TLR1 and TLR2 ligand binding domain under positive selection in avian TLR2A. A: Human TLR1. B: Mouse TLR6. C: Human TLR2.