Integrins are a family of cell surface transmembrane receptors，each consisting of an and a B subunit that bind to extracellular matrix (ECM) proteins and cellular counter receptors and associate with the cytoskeleton. In mammals，24 different integrins are generated through different combinations of 18 and 8 B subunits. A number of human congenital disorders have been associated with defective integrin-mediated adhesion，including the blistering disorder junctional epidermolysis bullosa，the bleeding disorder Glanzmann’s thrombastenia，leukocyte adhesion deficiency-I (B2 integrins in leukocytes) and leukocyte adhesion deficiency-III，nephrotic syndrome and interstitial lung disease and muscular dystrophy. Integrin alpha-V/beta-5 is a receptor for fibronectin and it recognizes the sequence R-G-D in its ligand.
