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Vitamin D-binding protein (DBP/GC-globulin) serves as the primary transporter of vitamin D metabolites (25OHD, 1,25(OH)2D) in plasma, maintaining their solubility and bioavailability. Structurally, DBP comprises three domains, with domain I harboring a high-affinity binding site for vitamin D metabolites. Beyond sterol transport, DBP binds monomeric actin with nanomolar affinity, preventing pathological actin polymerization in circulation-a critical function during tissue injury. It also interacts with immune cells, binding to surface receptors on B and T lymphocytes to modulate chemotaxis and inflammatory responses.
Reduced DBP levels correlate with severe liver diseases such as cirrhosis and acute-on-chronic liver failure, where impaired synthesis exacerbates vitamin D deficiency and actin scavenging dysfunction. In Itai-Itai disease, DBP loss in urine disrupts vitamin D transport, contributing to cadmium-induced osteomalacia 7. Genetic polymorphisms (e.g., Gc1F, Gc1S, Gc2) influence DBP’s binding affinity, linking specific alleles to viral infection susceptibility and autoimmune disorders like lupus. Low DBP levels also associate with non-alcoholic fatty liver disease (NAFLD) progression and type 2 diabetes, where pancreatic α-cell dysfunction arises from disrupted actin cytoskeleton regulation.
Common uses include IVD Assay standards, calibrators and controls, and metabolic studies.
Not a hazardous substance or mixture.
11 - Combustible Solids