Fig. 4.

4-1BB bound to utomilumab and urelumab. a Utomilumab Fab bound to 4-1BB at the junction of CRD-3 and CRD-4. b Urelumab Fab bound to 4-1BB at the N-terminal portion of CRD-1. c Receptor mutants N42R or M101R and I132R were chosen to disrupt respective urelumab or utomilumab binding sites. Urelumab or utomilumab antibody was incubated with captured wild type or mutant h4-1BB receptor and subsequently washed before binding was detected by the addition of anti-human IgG Fc-HRP. Data shown as mean with s.d. (N = 3). As predicted by the antibody-bound structures, utomilumab shows reduced binding to M101R and I132R h4-1BB mutants but not N42R while urelumab shows the opposite trend. hOX40 was used as negative control. Structures depict position of receptor mutants. Receptors are shown in forest green cartoon with mutation sites highlighted in red spheres. Utomilumab (blue), urelumab (red) are shown in transparent surfaces