Integrin ITGAL/ITGB2 is a receptor for ICAM1, ICAM2, ICAM3 and ICAM4. Integrin ITGAL/ITGB2 is a receptor for F11R (PubMed:11812992, PubMed:15528364). Integrin ITGAL/ITGB2 is a receptor for the secreted form of ubiquitin-like protein ISG15; the interaction is mediated by ITGAL (PubMed:29100055). 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 (PubMed:15356110). Involved in leukocyte adhesion and transmigration of leukocytes including T-cells and neutrophils (PubMed:11812992). Required for generation of common lymphoid progenitor cells in bone marrow, indicating a role in lymphopoiesis (By similarity). Integrin ITGAL/ITGB2 in association with ICAM3, contributes to apoptotic neutrophil phagocytosis by macrophages (PubMed:23775590). Heterodimer of an alpha and a beta subunit (PubMed:12526797). The ITGAL alpha subunit associates with the ITGB2 beta subunit (PubMed:12526797). Interacts with THBD (PubMed:27055590). (Microbial infection) Interacts with SARS-CoV Orf7a protein. Leukocytes. The integrin I-domain (insert) is a VWFA domain (PubMed:2537322). Integrins with I-domains do not undergo protease cleavage. The I-domain is necessary and sufficient for interaction with ICAM1 and F11R (PubMed:15528364). 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 activation by some physiological agents. Belongs to the integrin alpha chain family.