Figure 3. LRP6_ECD–Mesd Complex.

(A) MALS analysis indicates an experimental molecular mass (red line) of 199.8 ± 5.4 kDa for the LRP6_ECD–Mesd complex (blue line; elution profile in 10 mM Tris-HCl (pH 8.0), 150 mM NaCl, axis not shown) as observed by SDS–PAGE (inset) and in agreement with the calculated molecular mass for a 1:1 LRP6_ECD–Mesd complex (195.4 kDa).

(B) Raw images of the negatively stained LRP6_ECD–Mesd complex.

(C) Representative class averages of the complex show a skewed ring-like structure of similar dimensions to LRP6_ECD alone.

(D) 3D reconstruction of the LRP6_ECD–Mesd complex at 26 Å resolution (blue surface, left panel) (Figure S3). The apo LRP6_ECD reconstruction (density corresponding to tandem PE pairs colored tan and purple while density representing LDLR type A domains in light green) was real-space refined into density for the complex (blue mesh, right panel). The crystal structure of the mouse Mesd core domain (dark blue surface) was rendered at 25 Å resolution and manually placed into the remaining density of the reconstruction. Scale bars for (B) and (C) (140 Å), and (D) and (E) (50 Å) are indicated.

See also Figure S3.