Figure 1. Structure of the Toll-like receptor 3 (TLR3) extracellular domain (ECD) and model of the full-length receptor. A) A single leucine-rich repeat (LRR) loop highlighting conserved hydrophobic side chains (brown spheres) that form the core of the solenoid. B) A cartoon trace showing the curved solenoid, or “slinky” shape of the ECD. β-strands are shown as arrows on the concave surface of the ECD. C) A surface rendering of TLR3. In B and C, glycans are shown in green, sulfate ions in orange, and insertions in LRRs 12 and 20 in red. Transmembrane and cytoplasmic domains, based on previously reported structures, are shown in gray.