Human melanoma cells express a novel integrin receptor for laminin

• Published in: The Journal of biological chemistry 1989-09, Vol.264 (26), p.15642-15649
• Main Authors: Kramer, R H, McDonald, K A, Vu, M P
• Format: Article
• Language: English
• Subjects: Antibodies, Monoclonal; Biological and medical sciences; Cell Adhesion; Cell Line; Cell receptors; Cell structures and functions; Chromatography, Affinity; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Humans; integrin; Integrins; Kinetics; Laminin; Macromolecular Substances; Melanoma - physiopathology; Membrane Glycoproteins - analysis; Membrane Glycoproteins - immunology; Miscellaneous; Molecular and cellular biology; Molecular Weight; Receptors, Immunologic - analysis; Receptors, Immunologic - immunology; Receptors, Immunologic - isolation & purification; Receptors, Laminin
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)84880-9

This study sought to determine whether human melanoma cells express integrin-related receptors that mediate their adhesion to laminin. We found that antibodies against the integrin β1 chain blocked cell attachment to laminin-coated surfaces. Furthermore, immunofluorescence staining demonstrated β1 complexes in vinculin-positive focal adhesion plaques on the basal surface of cells attached to laminin substrates. Chromatography of detergent extracts of 125I-surface-labeled cells on laminin-Sepharose columns recovered two major laminin-binding proteins (100 and 130 kDa, reduced) that bound with high affinity to the columns and were eluted with EDTA. Both proteins were specifically immunoprecipitated from column fractions with monoclonal and polyclonal antibodies to the integrin β1 subunit, indicating that they form a noncovalent heterodimer complex. The α-like subunit is composed of a 30-kDa light chain that is joined by a disulfide bond to the 100-kDa heavy chain. This complex was not recovered from columns of fibronectin- or collagen type I- or IV-Sepharose. Laminin-binding by the αβ1 complex was independent of Arg-Gly-Asp or Tyr-Ile-Gly-Ser-Arg-like sequences, but required the presence of divalent cations. The 100-kDa α-like subunit was electrophoretically and immunochemically distinct from the other known α subunits, α1-α6. The results indicate that human melanoma cells express a novel laminin-specific integrin β1 complex which may mediate the cells' interactions with this ligand.