Cloning and characterization of a new intercellular adhesion molecule ICAM-R
Abstract
THE human intercellular adhesion molecules ICAM-1, 1C AM-2 and their counter-receptors, the β2 or leukointegrins, mediate a variety of homotypic and heterotypic leukocyte and endothelial cell-cell adhesions central to immunocompetence1. It has been found2 that cell-cell adhesion which is dependent on expression of the leukocyte function-associated antigen LFA-1 is not always blocked completely by antibodies raised against ICAM-1 and I CAM-2. Other leukointegrin ligands therefore probably exist, such as a glycoprotein of Mr 124K that binds LFA-1 and has been designated ICAM-3 on the basis of this function3. We have molecularly cloned a new member of the ICAM family, ICAM-R, which is related to ICAM-1 and ICAM-2. The complementary DNA encoding ICAM-R is 1,781 base pairs long and the protein has five extracellular immunoglobulin-family type domains. The mature cell-surface form of the ICAM-R protein has an Mr which varies from 116 to 140K in a cell type-specific fashion. Overall identities in protein sequence with ICAM-1 and ICAM-2 are 48% and 31% respectively, with the degree of similarity varying between individual domains. The high level of expression of ICAM-R on resting leukocytes of all lineages and its lack of expression on either resting or cytokine-activated endothelial cells indicates a pattern of expression distinct from ICAM-1 and ICAM-2. In common with ICAM-1 and ICAM-2, ICAM-R is a ligand for the β2-integrin CDlla/LFA-1 (CD18).
- Publication:
-
Nature
- Pub Date:
- December 1992
- DOI:
- 10.1038/360485a0
- Bibcode:
- 1992Natur.360..485V