ICAMs are members of the Ig superfamily of calcium-independent transmembrane glycoproteins. ICAM-1 is a ligand for the lymphocyte function-associated antigen (LFA) and Mac-1 integrins, as well as the major human rhinovirus receptor. The primary function of ICAM-1 is to provide adhesion between endothelial cells and leukocytes after stress or injury. The human ICAM-1 gene codes for a 505 amino acid transmembrane glycoprotein containing a 29 amino acid cytoplasmic domain, a 23 amino acid transmembrane domain, and a 453 amino acid extracellular domain. Recombinant Human ICAM-1 is a 49.5 kDa glycoprotein comprising the extracellular domain (453 amino acid residues) of ICAM-1. Monomeric glycosylated ICAM-1 migrates at an apparent molecular weight of approximately 72.0-80.0 kDa by SDS-PAGE analysis under reducing conditions.