ABSTRACT
The integrins are a large family of heterodimeric, divalent cation-dependent cell surface receptors that facilitate cell adhesion to extracellular matrix proteins and cell-cell adhesion. The α integrin subunits share an approximate 40% homology to each other and typically undergo posttranslational processing; for example, the αv subunit is proteolytically cleaved into a heavy and light chain which become disulfide linked. Integrin αvβ3 binds metal ions directly, and in the same concentration range necessary for ligand binding. The mechanisms by which βv integrins might be regulated include modulation by growth factors and cytokines. The αvβ3 integrin has been reported on many cell types in culture, including osteosarcoma, melanoma, malignant astrocyte, endothelial, keratinocyte, chick retinal neuron, fibroblast, placenta, endometrial epithelial, monocytes, platelet, osteoclast, neuroblastoma, and pancreatic ductal carcinoma cells, and in some cases on these cells in situ, as well. In the chick retina, an αv integrin is involved in neurite outgrowth on the substrate vitronectin.
