ICAM, an adhesion ligand of LFA-1, is homologous to the neural cell adhesion molecule NCAM.
Antigen-specific cell contacts in the immune system are strengthened by antigen-nonspecific interactions, mediated in part by lymphocyte-function associated (LFA) antigens. The LFA-1 antigen is widely expressed on cells of haematopoietic origin and is a major receptor of T cells, B cells and granulocytes. LFA-1 mediates the leukocyte adhesion reactions underlying cytolytic conjugate formation, helper T-cell interactions, and antibody-dependent killing by natural killer cells and granulocytes. Recently, ICAM-1 (intercellular adhesion molecule-1) has been defined as a ligand for LFA-1. Monoclonal antibodies to ICAM-1 block T lymphocyte adhesion to fibroblasts and endothelial cells and disrupt the interaction between cytotoxic T cells and target cells. In addition, purified ICAM-1 reconstituted into artificial membranes binds LFA-1+ cells. ICAM-1 is found on leukocytes, fibroblasts, epithelial cells and endothelial cells and its expression is regulated by inflammatory cytokines. LFA-1 has been placed in the integrin family of cell surface receptors by virtue of the high sequence similarity between the LFA-1 and integrin beta chains. The adhesion ligands of the integrin family are glycoproteins bearing the Arg-Gly-Asp (RGD) sequence motif, for example, fibronectin, fibrinogen, vitronectin and von Willebrand factor. Here we show that a complementary DNA clone ICAM-1 contains no RGD motifs, but instead is homologous to the neural cell adhesion molecule NCAM.
Simmons
D
D
Department of Molecular Biology, Harvard Medical School, Massachusetts General Hospital, Boston 02114.
Makgoba
M W
MW
Seed
B
B
D000595:Amino Acid Sequence; D000954:Antigens, Surface / Q000235:genetics*; D001483:Base Sequence; D015815:Cell Adhesion Molecules; D004247:DNA / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
D000954:Antigens, Surface; D015815:Cell Adhesion Molecules; D011994:Recombinant Proteins; D004247:DNA