title: Three-dimensional structure-function relationship of vitamin D and vitamin D receptor model.
abstract: On the basis of conformational analysis of the vitamin D side chain and studies using conformationally restricted synthetic vitamin D analogs, we have suggested the active space region concept of vitamin D: The vitamin D side-chain region was grouped into four regions (A, G, EA and EG) and the A and EA regions were suggested to be important for vitamin D actions. We extended our theory to known highly potent vitamin D analogs and found a new region F. The analogs which occupy the F region have such modifications as 22-oxa, 22-ene, 16-ene and 18-nor. Altogether, the following relationship between the space region and activity was found: Affinity for vitamin D receptor (VDR), EA > A> F > G > EG; Affinity for vitamin D binding protein (DBP), A >> G,EA,EG; Target gene transactivation, EA > F > A > EG > or = G; Cell differentiation, EA > F > A > EG > or = G; Bone calcium mobilization, EA > GA > F > or = EG; Intestinal calcium absorption, EA = A > or = G >> EG. We modeled the 3D structure of VDR-LBD (ligand binding domain) using hRARgamma as a template, to develop our structure-function theory into a theory involving VDR. 1alpha,25(OH)(2)D(3) was docked into the ligand binding pocket of the VDR with the side chain heading the wide cavity at the H-11 site, the A-ring toward the narrow beta-turn site, and the beta-face of the CD ring facing H3. Amino acid residues forming hydrogen bonds with the 1alpha- and 25-OH groups were specified: S237 and R274 forming a pincer type hydrogen-bond for the 1alpha-OH and H397 for the 25-OH. Mutants of several amino acid residues that are hydrogen-bond candidates were prepared and their biologic properties were evaluated. All of our mutation results together with known mutation data support our VDR model docked with the natural ligand.
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, 101-0062, Tokyo, Japan. yamada@i-mde,tmd.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Yamada
authors.forename: K
authors.initials: K
authors.lastname: Yamamoto
authors.forename: H
authors.initials: H
authors.lastname: Masuno
authors.forename: M
authors.initials: M
authors.lastname: Choi
mesh_terms: D000818:Animals; D006801:Humans; D008958:Models, Molecular; D008968:Molecular Conformation; D018167:Receptors, Calcitriol / Q000737:chemistry* / Q000235:genetics; D013329:Structure-Activity Relationship; D014807:Vitamin D / Q000737:chemistry* / Q000235:genetics
chemical_list: D018167:Receptors, Calcitriol; D014807:Vitamin D