VDBP (Vitamin D binding protein; also group-specific component and GC-globulin) is a 52-58kD, monomeric glycoprotein member of the ALB/AFP/VDB family of molecules. It is found in blood, urine and CSF, carries Vitamin D and its metabolites, and serves as an actin-scavenging protein. Mature mouse VDBP is 460 amino acids (aa) in length. It contains three albumin-type domains (aa 26-476) that are accompanied by 14 intrachain disulfide bonds. There are three potential alternative splice forms. One shows a deletion of aa 346-421, a second shows a 67 aa substitution for aa 345-421, and a third shows a 34 aa substitution for aa 346-423. All these variants involve the second and third albumin-like domains. Mature mouse VDBP (aa 17-476) is 77% and 90% aa identical to human and rat VDBP, respectively.