Localization of the binding site on intercellular adhesion molecule-3 (ICAM-3) for lymphocyte function-associated antigen 1 (LFA-1).
Intercellular adhesion molecule 3 (ICAM-3; CD50) is the predominant counter-receptor on resting T cells and monocytes for the leukocyte integrin, lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18), and may play an important role in the initial stages of the T cell-dependent immune response. Deletion of individual immunoglobulin superfamily (IgSF) domains of ICAM-3 and ICAM-3 IgSF domain chimeras with CD21 showed there is a single LFA-1 binding site in ICAM-3 and that IgSF domain 1 is necessary and sufficient for LFA-1 binding. Epitope mapping and functional studies performed with 17 anti-ICAM-3 monoclonal antibodies demonstrated that only some monoclonal antibodies, with epitopes wholly within domain 1 of ICAM-3, were able to block binding of ICAM-3 bearing cells to purified LFA-1, in agreement with the data obtained from the domain deletion mutants and CD21 chimeras. Analysis of a panel of 45 point mutants of domain 1 of ICAM-3 identified five residues that may contact LFA-1 as part of the binding site, Asn23, Ser25, Glu37, Phe54, and Gln75. These five residues are predicted by molecular modeling, based on the structure of vascular cell adhesion molecule 1 (VCAM-1), to cluster in two distinct locations on domain 1 of ICAM-3 on the BED face (Asn23 and Ser25) and on the C strand or CD loop (E37), the E strand (F54), and the FG loop (Q75). The residues, Asn23 and Ser25, comprise a consensus N-linked glycosylation site.
Klickstein
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LB
Center for Blood Research and Harvard Medical School, Department of Pathology, Boston, Massachusetts 21150, USA.
York
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MR
Fougerolles
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AR
Springer
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TA
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D001665:Binding Sites; D019556:COS Cells; D015815:Cell Adhesion Molecules / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D018604:Epitope Mapping; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins; D017384:Sequence Deletion; D013329:Structure-Activity Relationship
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D015815:Cell Adhesion Molecules; C483616:ICAM3 protein, human; D016169:Lymphocyte Function-Associated Antigen-1; D011994:Recombinant Proteins