Integrins are a class of adhesion receptors that link the extracellular matrix to the cytoskeleton and cooperate with growth factor receptors to promote celll survival, cell cycle progression and cell migration. Integrins consist of an alpha and a beta sub-unit. Each sub-unit has a large extracellular portion, a single transmembrane segment and a short cytoplasmic domain. The N-terminal domains of the alpha and beta subunits associate to form the integrin headpiece, which contains the ligand binding site, whereas the C-terminal segments traverse the plasma membrane and mediate interaction with the cytoskeleton and with signalling proteins.The VWA domains present in the alpha subunits of integrins seem to be a chordate specific radiation of the gene family being found only in vertebrates. They mediate protein-protein interactions.
Jiyao W et al.(2023). "The conserved domain database in 2023.",