| First Author | Edwards CP | Year | 1995 |
| Journal | J Biol Chem | Volume | 270 |
| Issue | 21 | Pages | 12635-40 |
| PubMed ID | 7539005 | Mgi Jnum | J:25635 |
| Mgi Id | MGI:73349 | Doi | 10.1074/jbc.270.21.12635 |
| Citation | Edwards CP, et al. (1995) Identification of amino acids in the CD11a I-domain important for binding of the leukocyte function-associated antigen-1 (LFA-1) to intercellular adhesion molecule-1 (ICAM-1). J Biol Chem 270(21):12635-40 |
| abstractText | Leukocyte function-associated antigen-1 (LFA-1) is a cell surface adhesion receptor for intercellular adhesion molecule-1, -2, and -3 (ICAM-1, -2, -3). Using human/murine chimeras of the I-domain of the LFA-1 alpha subunit (CD11a), we recently identified the epitopes recognized by eight monoclonal antibodies against CD11a that inhibit LFA-1 binding to ICAM-1. In this report, we determined that replacement of the entire human I-domain with the entire murine I-domain in CD11a completely abrogated LFA-1 binding to human ICAM-1 without affecting the gross conformation or heterodimer formation of LFA-1, as assayed by antibody binding. In order to assess which residues of the I-domain are responsible for binding to ICAM-1, we tested the ability of a panel of human/murine I-domain chimeras to bind to human ICAM-1. When complexed with CD18, all CD11a chimeras bound ICAM-1 at levels comparable to wild-type CD11a/CD18, indicating that the residues in these chimeras which differ in human and murine I-domains may not play a critical role in LFA-1 binding to ICAM-1. A series of point mutations of residues that are conserved between murine and human CD11a I-domains, as well as between CD11b and CD11c, were also generated. Substitution of alanine for proline at position 192 in the human CD11a I-domain abrogated adhesion of LFA-1 to ICAM-1. Antibody binding data suggested that this was due to conformational changes within the I-domain. Mutation of the aspartic acids at positions 137 and 239 to either alanine or lysine completely destroyed ICAM-1 binding. The conformation of LFA-1 alanine mutants was not significantly altered. This suggests that these aspartic acids are required for binding of human LFA-1 to human ICAM-1. |
