Integrin ITGAL/ITGB2 is a receptor for ICAM1, ICAM2, ICAM3 and ICAM4. Integrin ITGAL/ITGB2 is a receptor for F11R. Integrin ITGAL/ITGB2 is a receptor for the secreted form of ubiquitin-like protein ISG15; the interaction is mediated by ITGAL. Involved in a variety of immune phenomena including leukocyte-endothelial cell interaction, cytotoxic T-cell mediated killing, and antibody dependent killing by granulocytes and monocytes. Contributes to natural killer cell cytotoxicity. Involved in leukocyte adhesion and transmigration of leukocytes including T-cells and neutrophils. Required for generation of common lymphoid progenitor cells in bone marrow, indicating the role in lymphopoiesis. Integrin ITGAL/ITGB2 in association with ICAM3, contributes to apoptotic neutrophil phagocytosis by macrophages. Heterodimer of an alpha and a beta subunit. The ITGAL alpha subunit associates with the ITGB2 beta subunit. Interacts with THBD. The integrin I-domain (insert) is a VWFA domain. Integrins with I-domains do not undergo protease cleavage. The I-domain is necessary and sufficient for interaction with ICAM1 and F11R. In resting T-cells, up to 40% of surface ITGAL is constitutively phosphorylated. Phosphorylation causes conformational changes needed for ligand binding and is necessary for the activation by some physiological agents. Belongs to the integrin alpha chain family.