Vitronectin is a cell adhesion and spreading factor found in serum and tissues. Vitronectin interact with glycosaminoglycans and proteoglycans. Is recognized by certain members of the integrin family and serves as a cell-to-substrate adhesion molecule. Inhibitor of the membrane-damaging effect of the terminal cytolytic complement pathway. Somatomedin-B is a growth hormone-dependent serum factor with protease-inhibiting activity.
The SMB domain mediates interaction with SERPINE1/PAI1. The heparin-binding domain mediates interaction with insulin.
Sulfated on 2 tyrosine residues. N- and O-glycosylated. Phosphorylation on Thr-69 and Thr-76 favors cell adhesion and spreading. It has been suggested that the active SMB domain may be permitted considerable disulfide bond heterogeneity or variability, thus two alternate disulfide patterns based on 3D structures are described with 1 disulfide bond conserved in both. Phosphorylation sites are present in the extracellular medium.