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. ITGA5:ITGB1 acts as a receptor for fibrillin-1 (FBN1) and mediates R-G-D-dependent cell adhesion to FBN1. ITGA5:ITGB1 is a receptor for IL1B and binding is essential for IL1B signaling. ITGA5:ITGB3 is a receptor for soluble CD40LG and is required for CD40/CD40LG signaling (By similarity). 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 NISCH (PubMed:11121431, PubMed:14535848, PubMed:15229651). Interacts with HPS5 (By similarity). Interacts with RAB21 and COMP. Interacts with CIB1 (By similarity). ITGA5:ITGB1 interacts with CCN3 (By similarity). ITGA5:ITGB1 interacts with FBN1 (By similarity). ITGA5:ITGB1 interacts with IL1B (By similarity). ITGA5:ITGB1 interacts with ACE2 (By similarity). Interacts with ANGPT2 (By similarity). Proteolytic cleavage by PCSK5 mediates activation of the precursor. Mice die at 10-11 dpc. They show both extraembryonic and embryonic vascular defects, and severe abnormalities in the development of the posterior trunk. Belongs to the integrin alpha chain family.