Integrin alpha-5/beta-1 (ITGA5:ITGB1) is a receptor for fibronectin and fibrinogen. It recognizes the sequence R-G-D in its ligands. ITGA5:ITGB1 binds to PLA2G2A via a site (site 2) which is distinct from the classical ligand-binding site (site 1) and this induces integrin conformational changes and enhanced ligand binding to site 1 (PubMed:18635536, PubMed:25398877). ITGA5:ITGB1 acts as a receptor for fibrillin-1 (FBN1) and mediates R-G-D-dependent cell adhesion to FBN1 (PubMed:12807887, PubMed:17158881). ITGA5:ITGB1 is a receptor for IL1B and binding is essential for IL1B signaling (PubMed:29030430). ITGA5:ITGB3 is a receptor for soluble CD40LG and is required for CD40/CD40LG signaling (PubMed:31331973). (Microbial infection) Integrin ITGA5:ITGB1 acts as a receptor for Human metapneumovirus. (Microbial infection) Integrin ITGA2:ITGB1 acts as a receptor for Human parvovirus B19. (Microbial infection) In case of HIV-1 infection, the interaction with extracellular viral Tat protein seems to enhance angiogenesis in Kaposi's sarcoma lesions. Heterodimer of an alpha and a beta subunit. The alpha subunit is composed of a heavy and a light chain linked by a disulfide bond. Alpha-5 associates with beta-1. Interacts with HPS5 and NISCH. Interacts with RAB21 and COMP. Interacts with CIB1. ITGA5:ITGB1 interacts with CCN3. ITGA5:ITGB1 interacts with FBN1 (PubMed:12807887, PubMed:17158881). ITGA5:ITGB1 interacts with IL1B (PubMed:29030430). ITGA5:ITGB1 interacts with ACE2 (PubMed:33102950). Interacts with ANGPT2 (PubMed:32908006). (Microbial infection) Integrin ITGA5:ITGB1 interacts with human metapneumovirus fusion protein. (Microbial infection) Integrin ITGA5:ITGB1 interacts with human parvovirus B19 capsid proteins. (Microbial infection) Interacts with HIV-1 Tat. (Microbial infection) ITGA5:ITGB1 interacts with SARS coronavirus-2/SARS-CoV-2 spike protein. Proteolytic cleavage by PCSK5 mediates activation of the precursor. Belongs to the integrin alpha chain family.