Quantikine Immunoassay Control Set 925 Human Vitamin D BP

Vitamin D binding protein (VitD BP), also known as DBP and Gc-globulin, is a 58 kDa glycoprotein that circulates at high concentration in the serum and serves as a carrier protein for vitamin D. The transport of vitamin D by VitD BP is important for the function of a wide variety of tissues. VitD BP binds both the 25(OH) and the hormonally active 1,25(OH)2 forms of vitamin D. VitD BP is primarily expressed in hepatocytes and to a lesser extent in the kidney. It delivers vitamin D into cells by Megalin-mediated endocytosis. A selectively deglycosylated form of VitD BP known as macrophage activating factor (MAF) blocks the angiogenic effects of FGF basic, VEGF, and Angiopoietin 2. VitD BP enhances the chemotaxis of monocytes and neutrophils to the activated complement component C5a or C5a des Arg (a C-terminally processed form of C5a). The chemotactic cofactor property of VitD BP is eliminated by binding to 1,25(OH)2 vitamin D, but it is not altered by binding to 25(OH) vitamin D or actin.