ICAM proteins are ligands for the leukocyte adhesion protein LFA-1 (integrin alpha-L/beta-2). ICAM4 is also a ligand for alpha-4/beta-1 and alpha-V integrins. Erythrocytes. N- and O-glycosylated. Responsible for the Landsteiner-Wiener blood group system [MIM:111250]. The molecular basis of the LW(A)=LW5/LW(B)=LW7 blood group antigens is a single variation in position 100; Gln-100 corresponds to LW(A) and Arg-100 to LW(B). Belongs to the immunoglobulin superfamily. ICAM family. Blood group antigen gene mutation database