IMMUNOHISTOCHEMICAL AND MOLECULAR ANALYSIS OF BETA-1 AND BETA-3 INTEGRINS

The expression and function of integrin subunits was examined by immunohistochemical staining of normal and malignant tissues and by producing specific changes in avian beta-subunit cDNA that were subsequently expressed in mammalian cells. Most tissues express only a restricted number of integrins. These include primarily those thought to function as collagen/laminin receptors. With the exception of metastatic melanomas, tumors show a general down regulation of integrins. Structure/function studies of the beta-subunit show that the cytoplasmic domain is required for inclusion in adhesion plaques and for promotion of adhesive functions; that the transmembrane domain is required for subunit association, but not proper alpha-subunit selection; and that the amino terminal one third of the subunit must remain intact for subunit selection and ligand binding to occur.