Figure 6.

The σ3 protein. A) Ribbon diagram of the crystal structure of T3D σ3.⁷³ The cathepsin L cleavage sites in T1L are depicted in blue between amino acids 243 and 244 and between 250 and 251.⁶⁵ Surrounding residues, from amino acids 241 to 253, are shown in yellow. The C-terminal residues of σ3, from amino acids 340 to 365, are colored red. Tyrosine 354, which is altered in several PI,⁷⁵ D-EA,⁵⁹ and ACA-D viruses,⁷⁶ is colored green. The virion-distal end of σ3 is at the top of the figure, and the virion proximal end and N-terminus are at the bottom. B) An enlarged view of the boxed region of σ3 indicated in panel B is shown using the same color scheme. Amino acids 243, 244, 250, 251, and 354 are depicted in ball-and-stick representation. Figure and legend modified from: Ebert DH et al, J Biol Chem 277:24609-24617; ©2002 with permission from the American Society for Biochemistry and Molecular Biology.⁶⁵