Structure of immunoglobulin family of adhesion proteins

The defining structural characteristic of the immunoglobulin superfamily of molecules is a variable number of intramolecular loops linked by disulfide bonds. The molecules of this family, which play a role in leukocyte-endothelial adhesion, are ICAM-1, ICAM-2, and VCAM-1. ICAM-1 has 5 extracellular domains, ICAM-2 has 2 domains, and VCAM-1 can have either 6 or 7 domains due to alternate splicing.