The article discusses the nuclear vitamin D receptor (VDR) and its biological and molecular regulatory properties. It highlights the role of VDR in vitamin D action, particularly in calcium and phosphate homeostasis, bone mineralization, and remodeling. The VDR is a nuclear receptor that binds to 1,25(OH)₂D₃, the active form of vitamin D, and mediates its effects on various tissues, including the intestine, bone, and immune system. The study also explores the structure and function of the VDR gene, including its chromosomal location, polymorphisms, and their potential impact on bone mineral density and other diseases. The article reviews the role of VDR in feedback control of the vitamin D endocrine system, the catabolism of 1,25(OH)₂D₃, and its involvement in phosphate homeostasis. It also discusses the neoclassical actions of 1,25(OH)₂D₃/VDR in various tissues, including the immune system, central nervous system, and epithelial cells. The study provides insights into the structure/function of the VDR protein, including its functional domains, DNA binding, nuclear localization, and heterodimerization with RXR. The article concludes with the implications of VDR mutations and their potential impact on human health, emphasizing the importance of understanding the molecular mechanisms of VDR in the context of vitamin D biology.The article discusses the nuclear vitamin D receptor (VDR) and its biological and molecular regulatory properties. It highlights the role of VDR in vitamin D action, particularly in calcium and phosphate homeostasis, bone mineralization, and remodeling. The VDR is a nuclear receptor that binds to 1,25(OH)₂D₃, the active form of vitamin D, and mediates its effects on various tissues, including the intestine, bone, and immune system. The study also explores the structure and function of the VDR gene, including its chromosomal location, polymorphisms, and their potential impact on bone mineral density and other diseases. The article reviews the role of VDR in feedback control of the vitamin D endocrine system, the catabolism of 1,25(OH)₂D₃, and its involvement in phosphate homeostasis. It also discusses the neoclassical actions of 1,25(OH)₂D₃/VDR in various tissues, including the immune system, central nervous system, and epithelial cells. The study provides insights into the structure/function of the VDR protein, including its functional domains, DNA binding, nuclear localization, and heterodimerization with RXR. The article concludes with the implications of VDR mutations and their potential impact on human health, emphasizing the importance of understanding the molecular mechanisms of VDR in the context of vitamin D biology.