Figure 4.

Structure of TB19 with CD73.A, cartoon representation of the different conformational states of CD73. The CD73 N-terminal domain of CD73 is shown in beige and the C-terminal domain is shown in blue. Gray coils: linker elements connecting the two domains. Red spheres: zinc cofactor(s) bound by the N-terminal domain. S: substrate. Note that the structure of the complex with TB19 was obtained in the absence of substrate, which is not shown. B, two TB19 Fv domains binding one CD73 dimer in the intermediate conformation viewed from two different angles. Colors are as in A with the zinc and phosphate molecules shown as red spheres. The TB19 Fab (green) is shown in a cartoon representation. C, mapping of the epitope for TB19 on CD73. The coloring scheme is as B; residues interacting withTB19 are shown in green.