Figure 4.

Common binding mode predicted for hydroxy-D3 metabolites in the genomic site of the VDR crystal structure (PDB code 1DB1). (A) Docked poses of hydroxy-D3 metabolites (listed in Table 2) are shown with thin bonds and green colored carbons. For comparison, the co-crystallized 1,25(OH)₂D3 is shown with thick bonds and light brown colored carbons. All other atoms are colored by atom type (O: red, N: blue, S: yellow, H: white). Only VDR residues involved in polar interactions with the ligands are included. Hydrogen bonding interactions of 1α(OH) and 3(OH) groups common in docked poses are indicated with dashed lines. (B) Schematic summary of interactions formed by docked analogs listed in Table 2 in the genomic site of VDR. Interactions formed between VDR residues and OH substituents in docked poses of the analog series are indicated with dashed lines, colored distinctly for each OH group. For example, 24(OH) in poses of some analogs interact with H397 while in case of other analogs with H305 (light blue dashed lines). VDR residue labels are color coded: those involved in polar interactions are dark blue; those contributing to non-polar interactions are dark brown.