Figure 1. Characterization of the TC-CD320 complex.

(a) Thermostability curves for different TC-CD320 complexes, demonstrating decreased complex stability in the presence of EGTA as well as for the TCα-CD320 and TC-LDLR-A2 complexes. (b) Solid-phase binding assay quantitating TC binding to full-length CD320 (black) and to LDLR-A2 (red; n=5, error bars indicate S.D). (c) Overall structure of TC-CD320 complex showing TC (cyan) and LDLR-A1 and LDLR-A2 of CD320 (yellow and gold, respectively). The likely position of the EGF-like module (boxed) bridging the two LDLR-A domains is shown schematically. The transmembrane domain (yellow cylinder) and internalization motif of CD320 were not part of the expression construct. Orange spheres represent bound Ca²⁺ ions. Bound Cbl, sandwiched between the α and β domains of TC, is shown in pink and TC helix α5 is coloured green.