Gc-Globulin is also known as which protein?

• A. Vitamin-D Binding Protein
• B. Retinol-Binding Protein
• C. Transferrin
• D. Albumin

Answer: (A)

Gc-globulin is the vitamin D binding protein. It circulates in plasma, binding and transporting vitamin D metabolites such as 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, helping make vitamin D available to tissues. It also has a role in binding actin released from damaged cells, aiding in clearance. Among common plasma proteins, the one with this specific function of binding vitamin D is the vitamin D–binding protein. Retinol-binding protein carries retinol (vitamin A), transferrin transports iron, and albumin is a general carrier for many substances but is not the vitamin D–binding protein.