Figure 3. X-ray structure of TTR. The molecule is a homotetrameric protein composed of four monomers of 127 amino acids. Structurally, in its native state, TTR contains eight stands (A-H) and a small α-helix. The contacts between the dimers form two hydrophobic pockets where T4 binds (T4 channel). As shown in the magnified insert, each monomer contains one small α-helix and eight β-strands (CBEF and DAGH). Adapted from a model; PDB code 1DVQ (68).