Fig. 3. Experimental electron density and homodimeric assembly. (A) Unbiased experimental electron density from SAD phases. The map is contoured around the CTE of the upstream subunit of the VDR DBD–DR3 structure, which is shown as a C_α trace. (B) A portion of the 2F_o = F_c electron density map showing intersubunit dimerization contacts. (C) Stereo view of the dimerization interface in a van der Waals surface representation. (A) and (B) were made with Xtalview (McRee, 1999), and (C) was prepared with Ribbons.