Members of a family of tight calcium-binding proteins that are produced in response to vitamin D (1,25 (0H)2D3) binding to its receptor in the cell. Other members of this family include calmodulin, troponin C, and parvalbumin.
A metabolite of vitamin D; 25-hydroxyvitamin D is used to make the active form, 1,25 dihydroxy vitamin D. Synthesis of the active form takes place in the kidney.